so heres my question i might get a custom downpipe for my car,should i eliminate the cat?will it be bad for the car?and is my car gonna be really loud?im gonna leave the o2 sensor on though.

 

Its not bad for the car, and it will help performance decently.

It will be a little deeper, but not really louder.

You will have a check engine light though.

 

do you anything about the Tsudo downpipe?does that downpipe eliminate the cat?

 

i really dont about that downpipe but from what ive seen most do not eliminate the cat, what you can do if it doesnt is gut the cat and like sebba said it will set a engine light, but if you can take care of the light, when you go to emissions when they check under the car for a cat they will think you have one, i had a guy go into my stock ecu and put a fake code so i can pass and the engine light stays on trust me if i knew how he did it i would tell everyone on here, i have had it like this for a year and it hasnt hurt anything.

 

i dont have any type of emission laws down in beautiful MIA,i feel sorry for you guys who have to go through emissions,i cant even imagine the pain

 

well then your cool just i dont know if the light would hurt anything but i would try to get it fix unless anybody say anything diff.

 

I have a test pipe on my gst and ive actually never thrown a code. I still cant figure out why though lol.

 

^^^ Same with me on the GST lol.

Well, i dont know about that perticular DP. Where are you getting it from? As long as it aint ebay, its okay

 

If you have a '97 to '99 GS-T, I have a brand new 3 inch downpipe I'll sell ya for like $100...still in the box, never used.

 

Cat vs High Flow Cat vs Test pipe article in Import Tuner wayy back when. Gain from stock cat - high flow cat = 1whp. Gain from high flow cat - test pipe = 1whp. from stock - test pipe = 2whp. doesn't make a diff at all. but this was also on an S13 where the cat is i think 2.5" and it wasn't obstructing the flow from DP - Cat-back. Personally i don't see a point in geting the test pipe when all it does is possibly throw codes, and depending on where you are, fail emissions. high flow cat ftw.