[rpschultz13]

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If I live in a state without emissions testing (TN), is there any downside to installing a catless downpipe? It looks fairly straight forward to do myself with a lift.

If I decide to sell down the road, is it best to put it back stock or leave it in?

[B58-M340iX]

I'm catless and live in a non-testing state. Other than the smell (ethanol eases the smell), no downsides. Plus side is more spooly boi noises . Adding it back on likely depends on whether you sell privately or trade into a dealer. A dealer will likely want the stock downpipe (exhaust is questionable).

[rpschultz13]

No testing here in TN. Ever.

Good point about selling to dealer.

[DanG]

Down side is that you will have a gas smell in the cockpit. Get a catted downpipe.

[rpschultz13]

How is catted different than stock? Looks like it only gains 5-10 whp. Not sure if it’s worth it.

[DanG]

Originally Posted by rpschultz13

How is catted different than stock? Looks like it only gains 5-10 whp. Not sure if it’s worth it.

Gain a lot of extra engine sound.

[sspade]

Originally Posted by rpschultz13

How is catted different than stock? Looks like it only gains 5-10 whp. Not sure if it’s worth it.

There's a massive gain in flow from the turbo through the exhaust by deleting the cat, its only common sense.... with a tune, more like 20-30 whp gain. If you're not going to run a flash tune, don't bother. Cold start delete is a must.

[sspade]

Originally Posted by DanG

Down side is that you will have a gas smell in the cockpit. Get a catted downpipe.

With the windows down, at a stop- you're right.

All other times- you're wrong.


I carried a carbon monoxide detector for a while out of paranoia and never had an alert.

[coperlio]

Catalytic converters play a crucial role in reducing harmful emissions from your car's exhaust. Removing it increases pollutants like hydrocarbons, carbon monoxide, and nitrogen oxides, contributing to air pollution. While a catless downpipe can improve exhaust flow and potentially boost horsepower, it might not be as significant as you expect. In some cases, it can disrupt the air-fuel ratio, requiring additional tuning for optimal performance.