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      12-06-2019, 06:58 PM   #45
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Quote:
Originally Posted by chetrickerman View Post
The hard part of that is that where the Center part of the diffuser is, is a rear bumper mounting point. So you would have to drill partially through the rear bumper (the part you cant see), which most people wouldn't want to do.

That could look awesome though.
Especially on the M4 in my opinion with its bubble butt. Of course thereís plenty of room for a dual exit with a muffler bypass, so Iím guessing thatís the route this goes.
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      12-06-2019, 09:40 PM   #46
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Originally Posted by ntg44 View Post
Update: Just got my car back from my fabricator. V2 design in attached photo.

Changes from V1 include:
- smaller muffler
- changed exit side pipe from 4.0 in -> 3.0 in, matching the entrance side pipe
- Changed exhaust tip style from 1 single walled 4.0 inch tip to 2 x 4.0 inch double walled rolled tip


Goals of V2 Design:
- Reduce bassier frequencies and boominess
- Eliminate 3500 RPM rasp/resonance
- Make exhaust louder


Results of V2 Design:
- Exhaust is louder, in such an awesome way. No increased drone from V1, but a reduction of bassier frequencies and replaced with higher pitched tones. In my opinion, it sounds just like an RB26 from the inside and out, up to about 4000 RPM. After that, the tone goes nuts. I'm not super familiar with the N54/55 tones, but to me it sounds like a 2JZ if it was a little muddier/dirtier. But it doesn't sound as mechanical as the V1 tone, at least from my initial observations.

- 3500 RPM rasp/resonance is still there. But somehow it isn't louder than before at least from the inside, and since the exhaust as a whole is louder, it gets drowned out a little better. Not perfect, but eh, I'll take it.


The car is louder now, but that just makes driving with windows down on the 30 minute drive home in 45 degree Chicago weather all the more worth it. Even accelerating lightly from a stop puts a huge grin on my face.


Luckily, my fabricator had a GoPro in the shop, so we stuck it on the bumper and drove around for a bit. I'm waiting for the video, but we listened to it on the shop speakers after pulling back in, and from what I heard today - it's good. It's very, very good. He's supposed to send me the video sometime soon - I'll get it up on YouTube as soon as I can - you all need to hear this. I couldn't be more excited to share this with all of you who are following.
I'm so curious. If I added a second outlet right before the muffler to be a quad tip I wonder if it'll change the sound back to the farty s55. Could you also PM me the price for TOP gear to piece the exhaust?
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      12-06-2019, 10:23 PM   #47
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Quote:
Originally Posted by jboogie315 View Post
I'm so curious. If I added a second outlet right before the muffler to be a quad tip I wonder if it'll change the sound back to the farty s55. Could you also PM me the price for TOP gear to piece the exhaust?
Actually, It would be cool if the OEM flap could be installed in this to kind of work like the OEM set up. Then you would have straight pipes when the valve is open.
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      12-07-2019, 01:59 AM   #48
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I'd be curious to know what a single exit with an angled tip and a diffuser that only has one exhaust opening would look like. Might look like ass on these cars but it'd be an interesting mockup if anyone is good with photoshop lol
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      12-07-2019, 02:05 AM   #49
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Great work ntg44 !
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      12-07-2019, 03:52 AM   #50
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Quote:
Originally Posted by HyeM3 View Post
I'd be curious to know what a single exit with an angled tip and a diffuser that only has one exhaust opening would look like. Might look like ass on these cars but it'd be an interesting mockup if anyone is good with photoshop lol
Here's a picture of the V1 version of my exhaust. My inner JDM fan boy was actually the inspiration for this first iteration. Was designed to piss off purists. The premise was that if I could make the car sound like an RB, then it accomplished its purpose. Personally I like it, and even with the second opening on the diffuser still there, I think with the offset muffler and pipe visible it had a hot rodded look to it. Certainly would spark conversations and every car enthusiast on the road was rushing to pull up next to me to hear it when I had it. When you have something so obviously different, people notice. I wanted to stand out.

Unfortunately, the 4 inch fartcan exit was a little too bassy, and while it sounded good, it wasn't what I was looking for. Shrinking the exit pipe to 3 inches sped up the velocity enough to get rid of the low end tones. And the smaller muffler opened the volume up to the glorious result you hear in V2. So now my car is louder when I want it without any more noticeable drone than before.
Attached Images
 

Last edited by ntg44; 12-07-2019 at 05:16 AM..
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      12-07-2019, 05:58 AM   #51
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Quote:
Originally Posted by jboogie315 View Post
I'm so curious. If I added a second outlet right before the muffler to be a quad tip I wonder if it'll change the sound back to the farty s55. Could you also PM me the price for TOP gear to piece the exhaust?
An extra pipe pre-muffler with a valve as a muffler bypass is definitely possible. There are no packaging restrictions impeding the implementation of the second pipe. But there's no way this would be tolerable with OEM valve logic. It would be stupid loud, and in my opinion, most people probably wouldn't like it. You'd need a valve controller that only opens when you want it to for it to be tolerable. Just think of how loud AWE track exhaust is, and that's a dual exit. Single exits are even louder. You'd probably get some hearing loss with enough pulls. Forget going catless

Regarding the tone - the secret isn't in the muffler, it's in the merged equal length design (obviously we all know this). Regardless, this is a raspy ass engine, and a muffler bypass will be a louder, tinnier sounding version of what you hear now. If I were to do this, I'd most likely try to fit in a small resonator before the muffler bypass. It would look weird as hell underneath the car, but then there may actually be a chance that it doesn't sound horrible. If people really want to know, I guess I could just cut off the muffler and record it for everyone haha. Much cheaper R&D than implementing it for the sake of dual exit.

As for me, I have perfect tone and volume right now, so a muffler bypass just isn't something I'm personally interested in. I'm probably going to put that money into a custom single exit diffuser. We'll see.

Regarding pricing - it's best to contact TopGear directly. I wouldn't mind using my car for fab & fitment, but you'd need to see if shipping is something TopGear is interested in. I'm walking a fine line right now - if I start getting involved in shipping peoples' systems, even as a good will favor, I doubt mods are going to see it that way. I'm not a vendor, and don't want to be banned because someone might think I'm starting to smell like one.
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      12-07-2019, 06:44 AM   #52
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Directed towards others who want to venture into this custom route:

There are multiple different options you can actually take in terms of mufflers, outlets. It's not the muffler that is making that noise (although it does impact things such as the volume of the sound), it's the equal-length pipe design before they merge , this is what sets it apart as ntg44 mentioned.

You can even utilize a big muffler in the mid-section such as where the OE center resonator/crossover pipe used to be, and then merge them at an x-pipe behind the differential and mock up a quad tip system from there since there would be tons of room now. But the overall theme in order to accomplish this is equalization of the pipe lengths.

There are various resonated X-pipes on the market from Magnaflow as well that can be utilized as the muffler to replace the OE muffler, that way the only part you and your fabricator would need to worry about is simply getting equal-length pipes to feed into the inlets of the resonated X-pipe, and somehow route the outlets out to a quad tip.

and while I wouldn't recommend hacking up your current aftermarket exhausts, you certainly can do this as well and play with the rear section design to remove the current crossover section, add length to the passenger side to be near equal to the length of the drivers side, and then re-merge them at a new crossover section.
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Last edited by spool twice; 12-07-2019 at 06:54 AM..
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      12-07-2019, 12:57 PM   #53
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Quote:
Originally Posted by ntg44 View Post
Here's a picture of the V1 version of my exhaust. My inner JDM fan boy was actually the inspiration for this first iteration. Was designed to piss off purists. The premise was that if I could make the car sound like an RB, then it accomplished its purpose. Personally I like it, and even with the second opening on the diffuser still there, I think with the offset muffler and pipe visible it had a hot rodded look to it. Certainly would spark conversations and every car enthusiast on the road was rushing to pull up next to me to hear it when I had it. When you have something so obviously different, people notice. I wanted to stand out.

Unfortunately, the 4 inch fartcan exit was a little too bassy, and while it sounded good, it wasn't what I was looking for. Shrinking the exit pipe to 3 inches sped up the velocity enough to get rid of the low end tones. And the smaller muffler opened the volume up to the glorious result you hear in V2. So now my car is louder when I want it without any more noticeable drone than before.
Interesting, that doesnít look too bad. I think maybe then the single exit angled tip would look pretty bad ass then lol. With all the people that run completely catless setups on this platform Iím sure they wouldnít mind a bassy fartcan
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      12-07-2019, 02:17 PM   #54
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ntg44

I know you removed the secondary cats, but is there a way to keep the cats and also add resonators? Also is there a way to build a dual side exhaust similar to the stock setup? I understand space is a huge constraint.

Maybe something like the following setup:


I've seen these because that's how a NC Miata is setup, might not be big enough though for our cars to cancel out certain tones or frequencies.

I would love to go through with this, unfortunately I'm on the west coast and on the wrong side of the border. This sucks.
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      12-07-2019, 02:26 PM   #55
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Quote:
Originally Posted by EvoFire View Post
ntg44

I know you removed the secondary cats, but is there a way to keep the cats and also add resonators? Also is there a way to build a dual side exhaust similar to the stock setup? I understand space is a huge constraint.

Maybe something like the following setup:

I've seen these because that's how a NC Miata is setup, might not be big enough though for our cars to cancel out certain tones or frequencies.

I would love to go through with this, unfortunately I'm on the west coast and on the wrong side of the border. This sucks.

I'm sure there is a way to add resonators - just need to fit them within the clearances. And that muffler absolutely would work.

I was able to record a pull today. I didn't realize how close to the highway I was, so there's some background tire noise, but here's the best fidelity pull I got today:


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      12-08-2019, 06:59 AM   #56
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so smooth! Definitely sounds more classic straight-6. I need to measure my new pipes, I have a feeling that mine is still someone off-set from being 100% equal.
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      12-08-2019, 09:31 AM   #57
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Quote:
Originally Posted by spool twice View Post
so smooth! Definitely sounds more classic straight-6. I need to measure my new pipes, I have a feeling that mine is still someone off-set from being 100% equal.
Have you posted a video of your setup? Iím going to make this mod to my OE exhaust. Interested to know exact lengths to add after you measure your exhaust. Thank you for the detailed original post!
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      12-08-2019, 10:30 AM   #58
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Quote:
Originally Posted by evanyork View Post
Quote:
Originally Posted by spool twice View Post
so smooth! Definitely sounds more classic straight-6. I need to measure my new pipes, I have a feeling that mine is still someone off-set from being 100% equal.
Have you posted a video of your setup? I’m going to make this mod to my OE exhaust. Interested to know exact lengths to add after you measure your exhaust. Thank you for the detailed original post!
Read the thread; page 1 - 14"
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      12-08-2019, 12:44 PM   #59
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Quote:
Originally Posted by evanyork View Post
Quote:
Originally Posted by spool twice View Post
so smooth! Definitely sounds more classic straight-6. I need to measure my new pipes, I have a feeling that mine is still someone off-set from being 100% equal.
Have you posted a video of your setup? I'm going to make this mod to my OE exhaust. Interested to know exact lengths to add after you measure your exhaust. Thank you for the detailed original post!
He added a 14" Custom bended pipe and a flowmaster X pipe. I'm doing this same mod as it's one of best sounding exhausts I heard. I'm curious on how the magnaflow race mufflers that'll replace the secondary cats will sound. Probably clean up the sound a bit. I'm looking to have a normal maybe somewhat louder exhaust when valves are closed and an absolute monster with great tone when open. Spool twice has the closest tone I'm looking for, NTG exhaust also sounds really nice. Pretty amazing what they've done that heavy hitter exhaust companies couldn't do.

Last edited by ///Mani; 12-08-2019 at 04:03 PM..
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      12-08-2019, 01:06 PM   #60
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Originally Posted by ///mpower.nick View Post
Pretty amazing what they've done that heavy hitter exhaust companies couldn't do.
Yep, apply a bit of simple physics to it instead of marketing hype & BS and bingo...

I'm in discussions with a local custom / motorsport exhaust manufacturer about this.

Going to get moving on it in the new year..

I might be first UK equal length pipe S55 owner
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      12-08-2019, 01:21 PM   #61
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Quote:
Originally Posted by ///mpower.nick View Post
Quote:
Originally Posted by evanyork View Post
Quote:
Originally Posted by spool twice View Post
so smooth! Definitely sounds more classic straight-6. I need to measure my new pipes, I have a feeling that mine is still someone off-set from being 100% equal.
Have you posted a video of your setup? I'm going to make this mod to my OE exhaust. Interested to know exact lengths to add after you measure your exhaust. Thank you for the detailed original post!
He added a 14" Custom bended pipe and a flowmaster X pipe. I'm doing this same mod as it's one of best sounding exhausts I heard. I'm curious on how the magnaflow race mufflers that'll replace the secondary cats will sound. Probably clean up the sound a bit. I'm looking to have a normal maybe somewhat louder exhaust when valves and an absolute monster with great tone when open. Spool twice has the closest tone I'm looking for, NTG exhaust also sounds really nice. Pretty amazing what they've done that heavy hitter exhaust companies couldn't do.
His pic only shows equalisation if pipe length via a u bend after the secondary cats and before cross over.i can't see any flow master x pipe ? Can the op please clarify ?
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      12-08-2019, 03:22 PM   #62
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These clips sound great!
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      12-08-2019, 05:18 PM   #63
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I only have prototype photos (it's not the prettiest looking thing), but I can post the pictures once I can get back on a laptop.

The basics are on my design:

-Center resonator/crossover delete

-Added about 14-15" to the passenger side (effective length)

-Merged both pipes using a Flowmaster 815953 crossover chamber directly after the rear differential

-Route the pipes exiting the crossover back into the muffler inlets.

Once you get the car on ramps, you'll be able to see what I mean. I have all downpipes/midpipes intact with cats, so there are opportunities to improve upon it and deliver a higher-pitched howl by removing these.

Last edited by spool twice; 12-12-2019 at 07:59 AM..
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      12-09-2019, 02:06 AM   #64
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Quote:
Originally Posted by drgmt View Post
His pic only shows equalisation if pipe length via a u bend after the secondary cats and before cross over.i can't see any flow master x pipe ? Can the op please clarify ?
There's two cars referred to here.

spool_twice (the OP) has the x-pipe etc with OE rear silencer.

ntg44 has the single exit car with no x-pipe.
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      12-09-2019, 06:06 AM   #65
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Quote:
Originally Posted by ///mpower.nick View Post
I'm curious on how the magnaflow race mufflers that'll replace the secondary cats will sound. Probably clean up the sound a bit.
This is *slightly* off topic, but if you want to hear what a 100% stock exhaust sounds with 2nd cats replaced with the Magnaflow 14156 resonators, here is my previous exhaust video with the valves unplugged and stuck open:





There is a dedicated thread to this (Started by Alan I), so I don't want to de-rail this thread. But for roughly $300 USD installed, you cannot beat this mod as a low budget option. It got rid of all the nasty mid-high range rasp when on boost. It's not exactly what I'd call inspiring, but at least it's fixed. It also got rid of some of the low RPM side effects of open valves - for example, my manual shifter no longer rattles after this modification. Overall, it just makes the exhaust more pleasant and un-farty.
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      12-09-2019, 08:18 AM   #66
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Quote:
Originally Posted by ntg44 View Post
This is *slightly* off topic, but if you want to hear what a 100% stock exhaust sounds with 2nd cats replaced with the Magnaflow 14156 resonators, here is my previous exhaust video with the valves unplugged and stuck open:





There is a dedicated thread to this (Started by Alan I), so I don't want to de-rail this thread. But for roughly $300 USD installed, you cannot beat this mod as a low budget option. It got rid of all the nasty mid-high range rasp when on boost. It's not exactly what I'd call inspiring, but at least it's fixed. It also got rid of some of the low RPM side effects of open valves - for example, my manual shifter no longer rattles after this modification. Overall, it just makes the exhaust more pleasant and un-farty.

I have these resonators sitting in my garage, i really need to get off my ass and get them installed.
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