Downpipe and second cat options

[wilse23]

Afternoon all,

Trying to unpick and decide on the best mod options for my 2018 M4 comp. I know there are lots of combos out there and my preference ultimately is to get bm3 so I can tune to my liking. Personally I'm looking for maybe +50bhp nothing to crazy but most importantly i want the car to sound amazing. So other than buying a 6k akrapovich full exhaust what are people's experiences?

I have bought a vrsf dp which will decat but I assume you cannot just go and put in a mid pipe as this will remove the secondary cat and therefore MOT will fail?
Have people gone bm3 and dp's and the sound has improved dramatically, hard to gauge with all the videos and setups out there so trying to get a view on people's experience
Cheers

[SteveChester]

I have decat and BM3 and it's a pretty good sound - passes MOT as well. Looking to get MP exhaust as well.

Not sure about removing the secondary cat and MOT - I'd assume it will fail unless anyone else on here can confirm otherwise?

[wilse23]

Originally Posted by SteveChester

I have decat and BM3 and it's a pretty good sound - passes MOT as well. Looking to get MP exhaust as well.

Not sure about removing the secondary cat and MOT - I'd assume it will fail unless anyone else on here can confirm otherwise?

Cheers Steve, I agree about the MPE exhaust it sounds impressive and would be a good combo

[SteveChester]

Originally Posted by wilse23

Cheers Steve, I agree about the MPE exhaust it sounds impressive and would be a good combo

Decat and BM3 (with pops and bangs) is pretty good. I have MTC Motorsport downpipes and retained the secondary cats. Exhaust is up next once the lockdown has finished!

[bseis]

Currently have AR design Catless Downpipes and AA midpipe welded onto my stock ZCP mufflers. BM3 stage 2 tune with burbles turned off sounds amazing. Total cost including the BM3 tune was about $2,000. Very clean sounding and deepens the exhaust note tremendously. Would definitely recommend! Had just downpipes at first but installing the midpipe too completely changed the exhaust tone.

[wilse23]

Originally Posted by bseis

Currently have AR design Catless Downpipes and AA midpipe welded onto my stock ZCP mufflers. BM3 stage 2 tune with burbles turned off sounds amazing. Total cost including the BM3 tune was about $2,000. Very clean sounding and deepens the exhaust note tremendously. Would definitely recommend! Had just downpipes at first but installing the midpipe too completely changed the exhaust tone.

Thanks for the info! Question though, without any cats will it not fail emissions on the MOT?

[t5pilot]

Originally Posted by wilse23

Thanks for the info! Question though, without any cats will it not fail emissions on the MOT?

Yes it will fail. Apparently not an issue in Canada

[MAXRPM]

Originally Posted by wilse23

Cheers Steve, I agree about the MPE exhaust it sounds impressive and would be a good combo

Hi just bought 2016 m4, can i defat the the without a ECU mod ?????

[Tengocity]

If you're not that fussed about getting absolute max power then stick with standard DP, get the AA equal length midpipe, and pair it with a backbox of your choice. I've done that with a Remus backbox and it sounds brilliant. Way better than any other F8x I've heard. All IMHO of course!