Running a testpipe instead of a cat

[d3m0]

Will running a test pipe instead of a cat actually make a noticable difference in power?

Thanks

 

[LiquidOC]

Anytime you free up exhaust flow or intake flow, you'll get some difference in horsepower, however, in California, good luck passing emissions without a catlytic convertor installed.

 

[Pure92TSi]

I noticed a difference when i removed mine so i would say yes. It frees up the exhaust flow a lot.

 

[Booster-Shot]

Ive heard of gains up to 5hp from a cat delete. Plus high flow cats are pretty cheap considering. Im sure youll notice it. I got rid of my cat, to hell with emissions.

 

[MyBeatGSX]

Made a big difference in power here. In fact I'm boosting 4psi more thanks to the creep.

 

[johnnytsi]

I think the real gain is better turbo response!

When I assembled my home bilt 3" turbo back exhaust I flanged a 3" high flow cat for emissions day, and then built a flanged 3" test pipe for everyday driving.

I see ~200rpm quicker spool up on my fp3052 with the test pipe in vs running the cat.

John-

 

[d3m0]

awesome, can't wait to bolt mine on

thanks for the input guys

 

[JX6]

Does running without a cat make you throw a Check Engine Light?

 

[gamma500]

The difference in restriction is quite noticeable when the diameter of the pipe decreases..a cat itself is not terribly restrictive for the most part. I have checked exhaust pressure upstream from a 2" cat and 2" testpipe and seen a minor differential at WOT only.
I just put an low restriction 2" cat in place of my 3" testpipe so inspection time would be easier ( my usual "look the other way" guy went out of business) and now have the same max boost of 24 psi but with noticeably slower spoolup but, on the plus side, have less boost creep..when the ext. WG opens my boost stays steady at the set limit instead of dropping suddenly. Actually makes the car less spastic powerwise on the street with asmoother power curve albeit the car is not as quick on a WOT pull. Will be curious to see what my DSMlink log looks like now..my guess is ? 20-30 less maximum HP and slower getting there.

I could probably return her (2G GSX, T3/T04E, .50 trim, .63 A/R) to near testpipe shape with a custom 3" cat but actually am enjoying the better streetabilty factor..a trip to the drags would necessitate a testpipe obviously but for day to day life, at least with my increased power/boost setup, I sorta like that downsteam restriction..may even help maintain the precat exhaust temperatures up. I'll have to recheck what the EGT is showing now although, if the above is true, it may not be a greast enough temp change to be reflected preturbo, in the EM.

Cheers,
CM

 

[madmader]

Does running without a cat make you throw a Check Engine Light?

Anytime you have a post cat oxygen sensor your more then luckily to have a code set. It's job is to tell if the cat itself is working, with it gone it will trigger the light.

So on a 1G your ok but 2G, nope.

 

[TurboD17]

I was wondering where i could get an inspection sticker for my car cause as of right now it will not pass. I have an o2 dump which is illegal. I live in NJ and inspection blows here. Any ideas???