Downpipe questions ???

[Bigbm80]

I am going to be upgrading my car soon and I read somewhere that I should delete the u-bend and possibly the resonator in preperation for changing the pulley to a 3.4 and upgrade the cat and downpipe in the future. So I figured while I was at it I would do it all at once to make it easier. So what im planning on doing is getting a 3" downpipe with a cat and attaching a pipe to it in place of the u-bend and resonator and putting it where my old one used to be. My question is will that work, the reason I question my plan is because im not sure if i need to get something else in order for the larger downpipe to fit. Also if you have any suggestions or see any other flaws in my plan please let me know. THANKS!

[Swash]

I copied this from another post I just replied to - but it also applies to you.

On the list of performance modifications - a pulley drop is about #6, to be honest - when talking about a bone stock car.

You need to get (in no certain order):
1) An exhaust manifold upgrade - either PLog, headers, something
2) A catless - or hi-flow catted downpipe - get that U-bend gone ASAP
3) An improved air intake system - either home-made or complete system purchased - but it needs to be a FWI for best results.
4) Colder plugs - Autolite 104's or similar
5) A custom tuned PCM - preferably mated with some form of active, real-time scanning tool.
6) THEN - when you have done these things, at minimum, and you have A/F ratios dialed in, KR tuned out as much as you can, etc etc - THEN - you can drop a pulley size. The drop to a 3.4 is the most popular - but you have other options - personally, I think the 3.5 is underrated for beginning performance gains - but if you do these things, you can (typically) run a 3.4 without any negative ramifications.

As for the type/manufacturer of DP - RandomTech's reputation is not that great - ZZP's DP is good, from what I hear - but I also know that Hogan Performance makes a quality product.

Hogan Performance

-Swash

[Lawngoose]

^ X2 ... Swash is absolutely correct.

[Bigbm80]

O, well I forgot to mention that I already have a few mods in place, I have a cold air intake, I have aftermarket mufflers, 180 thermostat, and I put in colder plugs. So I have 3 and 4 and 1 and 2 are the ones that I assume you say i need to do and what i was planning on doing. As far as 5 goes i was always told that the PCM is the last thing that should be done. But my question still remains, do i need anything to make the new larger downpipe work seeing as it is in fact larger then what was there, or can I just take off the old one and bolt on the new one ?

[TheOtherNick]

Nope just bolts in.

[Bigbm80]

what size is the stock header outlet? Is it 2.5" or is it 3" ?

[Swash]

I'm assuming that you mean exhaust outlet?? GP's don't have stock headers - just manifolds. Exhaust is 2.25" out of the manifolds - then 2" after the "Y" pipe. (97-03, speaking)

-Swash