FAQ: Down Pipe Questions (Series I SC)

do any of you have a ZZP down pipe, if so did it bolt right up . im thinking about geting a 2.5" bolt up DP with cat. i need some in put. is there any different with the S1 and s2 were they bolt up? please help

get a 3" DP the 2.5 will not yield any gains. you will need the off road pipe and the cat separate because on the 95/96 rivs the cat is connected to the DP. on the GTP and 97+ rivs there is a flange that bolts to the cat which makes their install easy. yours must be welded in.
you will also need a different collector/dp gasket than the one they sell b/c ours is different. i just reused mine and it sealed pretty well.
i also used just 3" pipe in place of the cat, but FL has no emission testing.

well NY is hard on emissons, thanks for the help. so i can use it i just need to weld the car on? will it bolt up in place to the rear manifold?

http://www.zzperformance.com/grand_prix/products1.php?id=551&catid=110

when they say weld in do they mean to the rear manifold or to the cat? please let me know some more help would be good

ps nice post number 420 ooo yea

i got the 3" shorty. that is a bolt up for the mani and weld up to the cat. you will need to get a high flo cat separate

any one with a S1 and a S2 is there a different to wear they bolt up

Not to hi-jack the thread but can you weld the 3in DP to a stock cat on a 96?

no, there is not enough clearance. you could cut out the cat, move it down and weld it up to the dp, adding in a small 3" pipe in between.
but in stock form the DP will not fit with enough room to weld right.

k so plan b.. how did you get it to run with no cat? did u have to use an 02 sim or did u just get the pcm flashed?

neither, any car will run fine w/out a cat, but it will not pass emissions. the weird part is, mine rarely ever shows a code for no cat. when/if it does i just clear it and its gone for a long time. i guess the 96's were not as sensitive to rear 02's or else my car is just weird and it runs the same emissions w/out a cat.
but you can get a sin or pcm tune to make sure the ses light stays off.

Did u get rid of the u-bend as well?

we dont have a u-bend

you all can thank me later, its cool.

http://store.summitracing.com/egnsearch.asp?N=700+4294923429+4294908256+4294840137+4294908237+115+4294924755

Need to find out the diameter of these pipes... if they are larger than a stock down pipe?

they are 2.5"

I am thinking about adding a ZZP DP to my 1995 Riv as well as a 2.5 inch pulley and supporting mods. Has anyone tried a ZZP DP on this application? I am considering the 3 inch shorty or the 3 inch bolt-on w/cat. Will the bolt-on with cat fit right up to my existing stock cat back system or are there other mods necessary?

i had this same question about 3-4 months ago i was told it would work if you went with hogan , one for a bonnie

i have one quick question, im still confused on what would best fit the 95 riv a 3 in shorty or a 3 in full length weld in dp for the bonnie, do i need bolt on or weld on ones? my plans are to get a downpipe, delete the cat, and run 3in pipes to the Y or muffs, i havent decided yet. any help would be great i plan on doing these mods soon right as i get out of school for summer brake in a couple of weeks.

Since I got my stimulus check, that's probably what i'm about to do. I emailed zzp earlier about their bonneville dp and they said they would have to check on our application. When I find out if it will fit, i'll let you know if you're still in question.

hey man that will be great, i too have some money to spend and want to spend it on a dp pipe just need to konw what kind.

I just ordered my downpipe, I went with the 3" shorty, going to do a cat delete. Anyways, sorry for the delayed response, it took zzp a while to respond in between emails.

I'll post my questions followed by their answers.

Q: Is this the same application as the hogan bonneville
dp? Because i'm driving a 97 Riviera, and the hogan dp will fit
my car, I just need to know if yours would fit it as well. Thanks.

A: there are a few different downpipes for Bonneville. I'll check on
your application.

A: I cant guarantee it for sure without having a Riviera here.


Q: What about the shorty?

A: The shorty should work but you'd have to weld it in.



From my understanding, 97+ Rivieras have a flange on the cat, and the zzp shorty has a flange as well which bolts right up to the cat with no welding. 95/96 I'm pretty sure have to be welded in because the cat converter is welded to the downpipe? I'm not 100% on that. The bolt on only applies to the 97+. You could just do what i'm doing, buy the 3" shorty and run straight pipe in place of the cat, then use a reducer to step the 3" pipe down to 2 1/4" pipe and weld into your stock catback. Those are my plans anyways, yours would probably be a little easier, 3" shorty, or a 3" offroad (same as the shorty just longer to replace the cat) and then weld into your 3" catback from there.

thats alright i figured they might take awhile, but thanks for the info. i think im pretty much going to do the same setup with a 3in shorty for mine and do a cat delete and your right i am going to have to have it welded on with 3in pipes to the Y.

etosino2009 wrote:

thats alright i figured they might take awhile, but thanks for the info. i think im pretty much going to do the same setup with a 3in shorty for mine and do a cat delete and your right i am going to have to have it welded on with 3in pipes to the Y.

Shouldn't be too bad then maybe you could post the legnths/bends when you do it, might be handy for other wanting to run custom exhaust.

sounds good, i ordered the part couple days ago and is should arrive today once i get everything set up and installed ill post the #'s with pics.

Mine will be in on monday finally..