if i have a catless up-pipe, and put on a catless downpipe, but keep the third cat, should i or will i get a CEL. everything else is stock.

what are the advantages of the bell mouth design, divorced wastegate twin dumps, or stock DP mounts.

before the flames begin, I have spent the last three days doing searches and have not found exactly what i am looking for.

and finally, is there anyone in Houston who is willing to depart with there factory DP for $40

25 views and no reply, does anyone know anything about downpipe, do you know anything about your car???

I don't have a downpipe...

You will probably get a CEL with any exauhst system other than a cat-back. It's really questionable though and hard to say. With my turboback I retained 2 cats, one in the up pipe and the other in the mid pipe and I have a constant CEL for it, while I know someone who has only the cat in the mid pipe and does not get a CEL. It also has to do with whether your tuned or not and also how many upgrades you've done matter a little bit.

I got a CEL with just a catless uppipe. After I cleared it out it didn't come back until I got my catless downpipe put on (about 2 weeks later). You do realize that they sell O2 simulators, correct? I'm putting one on next weekend when I install the STi motor mounts/Samco intercooler/MAF inlet hoses. This *should* clear up my CEL for good. While I'm at it I'm also doing the "resistor mod" for the uppipe, just to be sure that CEL doesn't come on again. Oh, and EGT/Boost gauges will be going in next weekend too.....should be a good weekend if everything goes as planned!!

i have just heard about this simulaters this morning, but have not found anything on them.

does it just give a varying output so the computer sees a change?
also, do you only need the resistor mod for the up-pipe if it doesn't have the EGT gauge in it?
where did you get your simulator and how much was it?
do you still have the third cat?

I'm not sure exactly how the simulator works. I got my sim from Buschur Racing along with my downpipe, although he does sell them seperately for $50 here.

You really don't *need* to do the resistor mod, most people do it for peace of mind. People have had issues with the stock probe backing out of an aftermarket uppipe. Personally I'm going to take the stock probe out, do the resistor mod (it's a whopping $1 part and takes 5 minutes to do), and stick an aftermarket EGT probe/gauge in it's place. Yes, I realize this won't be "accurate", but all I'm looking for is a change in temp from what is normal, not necessarily an "accurate" reading. If you have no plans for an EGT gauge people have just stuck a bolt in the EGT bung.

I am 100% catless. My car smells like a snowmobile.

nice!

Not to thread hijack......but aren't you the guy that knows Seth Gustine at ABB Vetco Gray?? I talked to him the other day and he said he just had lunch with "Wheeler" and that I knew who that was. I could have sworn he said you were already catless running just a straight pipe.....but maybe I'm confused.

yeah, thats me, i only have an axle back straight pipe(replaced the muffler section). i put in an up-pipe about 3 weeks ago and was thinking about a downpipe as well. my up-pipe is leaking a little, so when i go to fix that, i wanted to make it worth the time to take everything apart

Get rid of the cats, live with the possibility of code p0420. It doesn't harm anything. Go with whatever you can afford. HKS down pipe gets rid of two cats and is teh cheap. Bellmouth tend to cost more and may benefit you with the addition of a big turbo in the future, not sure of the benefits with td04.
dominic

I got a CEL just replacing the downpipe (with a Bosal catless one). CEL fixes are cheap and easy.

I replace both up and down pipes and it took over 1000 miles before I got a cel.

Im running catless now and have been for 8000 miles or so w/o any CELs at all. Of course I have a Godspeed DP and UP that has the "fake" cat thing where the O2 sensor goes. They guarantee it wont trigger any CELs too.

Godspeed's website