down pipe question

are there any down pipes that dont remove the precats? i would like to remove them but i hve emission checks:shakehead so yea.. cant do that i just want to open up my downpipe more so i can get some more power. and ik that a new DP will help.

I think 3sx has them.. or maybe it was DR... hmm check them out..

but if it was me. I would just keep the old exhaust.. and put it on to pass.. then take it off for the rest of the year... but thats just me..
Jason

yea thats an honest cheatin's man answer.....and mine to. keep the old exaust to pass the stinkin test.

I've been told that you can pass emissions without precats. from my understanding, precats only are needed til the car is warm, then the cat can do all the work. i may be wrong, but that is my understanding

correct however most downpipes take out the main cat

correct however most downpipes take out the main cat
Not necessarily. There are a range of choices for ones that keep the main cat or ones that delete it.

ooooh damn i know the answer to this!

your precats clean your exhaust until your car is warmed up, then the main cat comes into play. once your car is warmed up, no one can tell the difference like new2 said. so just drive around for like 30 minutes before inspection.

as for the downpipe, the stillen just totally removes the main cat, which you aren't looking for.

for a vr-4
http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=1064
works but needs holes for drilling - http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=26723

n/a
http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=1063

all these hours of reading old threads has finally paid off. i feel on top of things.

Not necessarily. There are a range of choices for ones that keep the main cat or ones that delete it.

I didn't say all.. I said most..

dang computer.. double post again

I've been told that you can pass emissions without precats. from my understanding, precats only are needed til the car is warm, then the cat can do all the work. i may be wrong, but that is my understanding

It has to do with the chemistry of it, catalysts are enzymes, and enzymes can only work under their optimum conditions (temperature and ph especially) when they are far from their optimum conditions then they are "bent" out of the correct shape and do not peform their functions.

The catalysts in the main cats are made to be used when the car is warm, so when it is cold they are "bent" and do not work properly, the opposite goes for the pre-cats, they dont work well when the car is warm.

It has to do with the chemistry of it, catalysts are enzymes, and enzymes can only work under their optimum conditions (temperature and ph especially) when they are far from their optimum conditions then they are "bent" out of the correct shape and do not peform their functions.

The catalysts in the main cats are made to be used when the car is warm, so when it is cold they are "bent" and do not work properly, the opposite goes for the pre-cats, they dont work well when the car is warm.
so that being said is it bad to remove the precats? and for the ppl that were posting i dont really wanna remove any of the cats bc of emissions. but i wanna free up some air for quicker spool.

also forgot to say they dont check my exhaust here where i live they just hook it to the comp and check for the cat with a mirror. and i dont think they look for the precats, so i wouldnt have to worry about them checking to make sure my exhaust is ok, my other car they check the exhaust but only bc its fwd. they dont have an awd dyno to run my car on to check the exhaust.... not sure if they check ur exhausts where u guys are or not.

so that being said is it bad to remove the precats? and for the ppl that were posting i dont really wanna remove any of the cats bc of emissions. but i wanna free up some air for quicker spool.

It would be fine to remove the precats, it would only affect the car until the exhaust got up to temp (not long) that is why one of the first things vr4 owners do is gut the precats.