d/p question...

[jeepgclwj]

I just ordered me a set of poly motor mounts and a 2.5" d/p w/cat from ZZP. Should I have gotten the 3". I am only planning on modding enough to support a 3.4 pulley safely. I thought I read I would loose a little power out of the hole if I got the 3 "..

Do I need to call ZZP and change my order or should I be ok with this set-up?

[BNaylor]

Nothing wrong with the 2.5" DP. No one has been able to prove scientifically other than speculation and sheer B.S. the 3" performs any better than the 2.5" in the areas of reducing knock retard, increased power or track times. The only exhaust mod I've ever seen a notable improvement is with headers. Also, some exhaust backpressure is required. Plus with headers the downpipe is not necessary and could be a waste of money if you ever plan on installing headers. But if you have no aspiration of going to headers then you should be OK.

[jeepgclwj]

I was thinking of headers in the future but I have a pretty good time in the car as it sits now. If I can get a noticeable gain from now till the pulley safely I think I will be satisfied with staying at that point. I shouldnt need headers to safely run a 3.4" pully, right?

My next mods before swapping pullys are going to be the crossover pipe and the front PEM. I think thats right. At that point I will have the FWI, Intense PCM, 180 t-stat, Poly mm, 2.5 d/p w/cat, ZZP crossover?, and front PEM?... Should at that point be able to run a 3.4 pulley safely? I was wondering bNaylor, you told me in the past it would be a waste of money running 3.5" pully. Is it that noticeable a differance between the 3.4 & 3.5 pully as far as performance and being safe to run as far as KR? Would running the 3.5 over a 3.4 really help me as far as the KR versus the 3.4?

CMD

[BNaylor]

Actually headers is the ideal solution to reducing KR even with a 3.4" SC pulley but you should be OK. Not counting an intercoooler. But there is the cost factor. In my case I use a 3.0" pulley so I am better off with headers. Plus headers have the most notable power gains actually felt in the seat of your pants. However, I would not assume it (KR) is going to be OK even with your planned mods until a KR check is done with a scanner capable of giving KR readout in degrees and in real time operation especially at WOT (burst KR) or a program such as Autotap running on a laptop computer. So after of all planned mods with exisiting are installed check the KR and record.

The best mod you have from what I can see is the re-programmed PCM module regardless of brand since it will support undersize SC pulleys better due to the modified programming versus stock. Of course, the DP and hi-flow CAT will also help. It is better safe than sorry and it looks like you have done your homework.