So i have my sights on doing a Apexi WS2 exhaust on my S. I no they are rather quiet so i was thinking of doing the cat delete pipe along with this to gain a little power and better sounds out the exhast. Howver i am not to knowledgable on this whole idea. If i where to go ahead with this idea would i have to switch the cat back in when i need to get it inspected? ( i prabably would just thought i would ask), and what kind of gains and sounds levels would i expect from doing a procedure like this? Also are the Cat delete pipe direct bolt on for easier installation? do S2k owners who go this route see a difference or see that it is better to do then not? Basically im just looking for some feedback on this subject because im hooked on it... but if its not the smartest idea i might try something else. Thanks for any help you guys provide!

 

Well i dont think that you will notice much difference in sound with a Test Pipe (what you call a cat-delete pipe). At least I didnt with my stock exhaust. If i strained my ears at 3-5k i might notice a little sound but it was hard to tell. However, with a cat back system that amplifies the exhaust note maybe it would be more noticeable.

I have never dynoed my car but i could tell a different with the test pipe. Probably more than the whole exhaust system. I have invidia V3 which is very loud to begin with. Id be curious to know what it would be like with a cat on and my exhaust.

For emission purposes I kept my cat to put back on for inspection. I recently got my 96 truck emission tested and he just hooked up to my OBDII. I asked him if thats all he does and he said yea. I explained my situation and he said he doesnt check for Cats. Just the code reader and gas cap test. With a TP obviously you will throw a code so you will need to either get a mechanical fix (what i did) or an O2 simulator. I have probably 3000 miles on mine and no code yet!
Im no expert in OBDII....so I dont know if there is anything in the background that doesnt give a check engine that would show up in an emission test. Id say do some research and see what kinda emission tests are done in your area. In most cases if you fail i think there is something where you can get a free retest. So if you fail, just throw the cat back on and retest.

Bottom line - very happy with my TP I say go for it. Great bang for your buck.

Nate

 

I agree... the sound is not all that different without the cat (a little louder and more raspy) If you were running a louder exhaust than it might be amplified more, but with a quiet exhaust you will be fine.

As far as removing your cat, I would only recomend it if you were planning on re-tuning the car. I was running a test pipe and when I put the cat back on I gained 3hp and some tourque thru out the entire RPM range (had I tuned the car while running a test pipe, I could have gotten some gains I'm sure). I too thought the car was quicker without the cat, but the dyno doesn't lie and it said I was making less power .

If you want to take the cat out I would recomend getting a Hytech long tube header (primaries end at the exhaust instead of where the cat shoud start) Its pricey and should still be done with tuning, but it wil make the most power and can be made to mate right up to you apexi exhaust

 

this is great guys, i was just wondering where can i buy a test pipe and how much do they cost and are they bolt on parts? Im just curious cause i may or may not do this im just trying to figure out what to expect.

 

TP's are for sale here in the "For Sale" section and some sponsors carry them. They are also on eBay EVERYDAY. Be sure to get the mechanical fix installed or you will get a CEL quickly.

You will get some more 'dirt' on the ends of you exhaust pipes.

Over 7,000 with my TP and no CEL's.

https://www.s2ki.com/forums/index.php?showt...hl=o2+simulator