Catless Downpipes for GTS

[Vladiz93]

Hello,

My GTS is for tracking, have owned it for 3 years.

Can I just run catless downpipes on it without a tune or do I need a tune as well?

-Drew

[SYT_Shadow]

I think you need either a tune or another way to remove the CEL you're bound to get. I hear defoulers and the other methods regular Ms use to get around this works fine, but haven't tried it myself

It would seem like a primary decat is a smart option for heavily tracked cars of any kind. Less heat in the engine, less heat in the cats, more sound, a little more power

[JustAnothaM4]

I'm running Akra downpipes with defoulers without a tune and it works perfect! No Cel or anything.

[SYT_Shadow]

Originally Posted by JustAnothaM4

I'm running Akra downpipes with defoulers without a tune and it works perfect! No Cel or anything.

It must sound pretty loud! and you retain the secondary cats to help cut down on the sound

[JustAnothaM4]

Originally Posted by SYT_Shadow

It must sound pretty loud! and you retain the secondary cats to help cut down on the sound

I'm switched to the full Akrapovic exhaust so all cats are removed. Just has a resonator to cut down the rasp. Not loud at all...I wish it was louder.

[mapster37]

Originally Posted by JustAnothaM4

I'm running Akra downpipes with defoulers without a tune and it works perfect! No Cel or anything.

Which defouler are you running, where did u purchase?

[JustAnothaM4]

Originally Posted by mapster37

Which defouler are you running, where did u purchase?

I dont remember the size defouler I used but, I got them from O'Reilly.
https://www.oreillyauto.com/shop/b/i...r/ebd2ebf2935a

[deemack79]

Originally Posted by SYT_Shadow

I think you need either a tune or another way to remove the CEL you're bound to get. I hear defoulers and the other methods regular Ms use to get around this works fine, but haven't tried it myself

It would seem like a primary decat is a smart option for heavily tracked cars of any kind. Less heat in the engine, less heat in the cats, more sound, a little more power

Defoulers work 100% double stacked and no CEL and no need to turn off via BM3

[SYT_Shadow]

Originally Posted by deemack79

Defoulers work 100% double stacked and no CEL and no need to turn off via BM3

Great information. Did you gain any power by just removing the downpipes as there's no tune involved?

[deemack79]

Originally Posted by SYT_Shadow

Great information. Did you gain any power by just removing the downpipes as there's no tune involved?

Not sure. the DP's were the last piece to be FBO. I'm sure you'll gain a few along with quicker turbo spool.

[mapster37]

Originally Posted by deemack79

Defoulers work 100% double stacked and no CEL and no need to turn off via BM3

How did the O2 sensors fit with the spacers? Any rubbing, looks like a tight fit in there with the oem down pipes. But maybe with catless there is more room??

[deemack79]

Originally Posted by mapster37

How did the O2 sensors fit with the spacers? Any rubbing, looks like a tight fit in there with the oem down pipes. But maybe with catless there is more room??

You just have to be patient and snake them in right. Nothing crazy though….

[JustAnothaM4]

Originally Posted by SYT_Shadow

Great information. Did you gain any power by just removing the downpipes as there's no tune involved?

Yes! There is definitely a power gain without the tune. I had a thread about my dyno results on my GTS and I'm hitting 497rwp on the stock tune w/ basic bolt-ons.

[SYT_Shadow]

Originally Posted by JustAnothaM4

Yes! There is definitely a power gain without the tune. I had a thread about my dyno results on my GTS and I'm hitting 497rwp on the stock tune w/ basic bolt-ons.

I saw that thread, power seemed incredibly high. I've dyno'd GTS1 on a dynojet, got 445whp STD where my CS got 431whp STD.
Very disappointing results.

I will dyno GTS1&2 together come springtime.