Should I go catless or catted downpipe (with stock turbo)?

[SavagePassenger]

Thanks for all the input - thinking I'm gonna go catless.

As a side question to does anyone know if the downpipe diameter makes any difference with a catless DP? I was trying to decide between some like the AMS , Evolution Racewerks, and Fi exhaust (only because I might get their full exhaust system). Seems like the diameter after the connection to the turbo housing can be anywhere from 3.5" to 4.5" , and some downpipes even go to 5 inch. I don't know if there's actually a performance difference between one like the Fi or Armytrix that look like a smaller diameter, vs one that tapers from 4.5" down to the factory exhaust connection.

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[FLtrackdays]

Thanks for all the input - thinking I'm gonna go catless.

As a side question to does anyone know if the downpipe diameter makes any difference with a catless DP? I was trying to decide between some like the AMS , Evolution Racewerks, and Fi exhaust (only because I might get their full exhaust system). Seems like the diameter after the connection to the turbo housing can be anywhere from 3.5" to 4.5" , and some downpipes even go to 5 inch. I don't know if there's actually a performance difference between one like the Fi or Armytrix that look like a smaller diameter, vs one that tapers from 4.5" down to the factory exhaust connection.

I would reach out to @NitroYellowMKV. The dude is a wealth of knowledge with downpipe and tailpipes

 

[Mason]

Fast cars are catless

 

[Extreme Power House]

Thanks for all the input - thinking I'm gonna go catless.

As a side question to does anyone know if the downpipe diameter makes any difference with a catless DP? I was trying to decide between some like the AMS , Evolution Racewerks, and Fi exhaust (only because I might get their full exhaust system). Seems like the diameter after the connection to the turbo housing can be anywhere from 3.5" to 4.5" , and some downpipes even go to 5 inch. I don't know if there's actually a performance difference between one like the Fi or Armytrix that look like a smaller diameter, vs one that tapers from 4.5" down to the factory exhaust connection.

The bare minimum downpipe diameter you should consider is 4". Although a 5" downpipe won't offer substantial power improvements on a stock turbo, it will provide additional airflow, which is beneficial when you upgrade your turbo.

It's worth noting that the diameter of your downpipe can also influence the sound of your exhaust: the larger the diameter, the deeper the mid-range sound will be.

Evolution Racewerks stands out as the superior choice among the options you listed. Their downpipes are handcrafted in the US, showcasing exquisite welds and a high-quality finish.

 

[Awales74]

Thanks for all the input - thinking I'm gonna go catless.

 

[SavagePassenger]

Another related question - with a custom tune is it a big deal to switch from a catless downpipe to a catted one later on(like the active autowerke)?

I’ll be getting tuned with ecutek soon and was planning on asking my tuner, but was curious if anyone here might know. I figured that might be something that needs a retune/ adjustment though I really don’t have any idea.

 

[Awales74]

planning on asking my tuner

This really is the answer. But to give you general idea, once you tune your car you really should monitor and make sure it's running ok. The tuner has tuned out the tolerance the OEM built in. This involves taking some logs occasionally and looking for things like knock retard (KR). See this consistently then go talk to your tuner. After switching downpipe from tree murdering catless, log, check to see if KR. If you get it then you should retune.

 

[FLtrackdays]

Another related question - with a custom tune is it a big deal to switch from a catless downpipe to a catted one later on(like the active autowerke)?

I’ll be getting tuned with ecutek soon and was planning on asking my tuner, but was curious if anyone here might know. I figured that might be something that needs a retune/ adjustment though I really don’t have any idea.

This car does fantastic with these mods. My little MX5 or S2K definitely needed the air/fuel ratios trimmed. This B58 is really robust and has a lot of wiggle room. Like @Awales74 said, can’t hurt to touch base with your tuner. I wouldn’t think twice of swapping em out if I stopped tracking or became deaf and couldn’t hear the wonderful sound. The active autowerke is a fantastic cat option! If you’re not tracking a lot, you probably won’t burn it up either.

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