hey guys picture this with me. I currently have a pde dp and a tanabe cat back. if you are familiar with the pde dp it is 3in in diameter until it gets to the end where it connects to the cat back where it shrinks down to a 2 1/2 to a 2 3/4 roughly. also on the cat back it starts at a 2 1/2 to a 2 3/4 again then opens up to 3in all the way back. now my question is will this restrict flow in any way to where i would lose power. or should i go and get this section removed and have a 3in pipe welded in its place so 3in all the way through? if i do this would i lose to much back pressure? any help is greatly appreciated

Jess

my mods:

pde up/dp
tanabe exhaust
removed intake silencer

 

Dude, I live in Mililani too and have the down pipe and exhaust. Actually, you are correct. The exhaust does cause a bottle neck which does restrict flow. There are definitley better exhaust systems available which provide a consistent 3' diameter. However, are you willing to spend the money? I run fine at SCCA and would suggest spending the money on something else like tires, boost controller, etc. I personally like my set up as a little restriction/back pressure theoretically will give you more low end/mid range. Let me know if you have any other questions. Following are my mods that I run at SOLO II:

SCCA WRX 151

PDE Up pipe/DP
Tanabe exhaust
Vishnu Pulley
1 Stage Colder Denso Irridiums
Dual Stage Turbo XS Boost Controller Set @ 16.5 PSI
EMI Adapter
Toda Flywheel
Dual Friction Centerforce Clutch
Cusco zero's, upper front / rear stress bar, rear sway bar, Camber plates
SSR's w/ Kumho V700's

 

wrx151,

do you drag your car? if you do what kind of times are you getting with that dual stage boost controller. oh yeah what part of mililani you at and what color is your car?

4080

 

2 1/2" will support more HP then you will probably ever have on your car. Leave it as is and get an uppipe.

 

My DP tapers down to fit the stock exhaust. Good enough for me.
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Dude, I haven't run my car for a long time. My best, with my stock clutch, stock flywheel, stock pulley and stock up pipe, I ran 14.1. I'm really not sure what it'll run now since all the mods. I mostly race at SOLO II at the SCCA track. My car is black w/ the Japan STI kit, STI fog light covers, JUN eye lids and white SSR's (Bronz if I'm heading down to the track). You can't miss it.

My suggestion is to put in your up pipe next.

SCCA WRX 151

 

Hey Jess, first of all Larry, aka WRX151 is one fast **** at soloII events. But soloII and drags are two different beasts. ie, I'm not sure how effective his car will be at the quarter due to his "autocross" set-up. That being said, my cusco DP is built to fit the stock cat-back as well. Good enough for 13's. I think your biggest restriction may be the muffler itself. My opinion on exhausts for our cars is: noise=power. ie, the loudest will generally yield the highest HP/TORQUE gains.

Oh yeah, experience/seat time is the cheapest and most effective way to lower times in any race venue

 

The only thing that might hinder Larry's 1/4 mi times might be his suspention setup, but your talking maybe tenths.

Also, he has a Tanabe catback, which is one of the lest restrictive mufflers.

4080, my question's for you would be, How much HP are you looking at making? Rexstang has the same setup and has gotten into the 12's.

 

Jess, IslandX & HRWRX are absolutely correct! By the way, thanks for the props Islandx. The real question is what venue of racing do you want to set your car up for, what is your target HP and how much are you willing to spend? Primary example, my friend Scott went full blown w/ a much larger turbo, front mount intercooler, STI injectors, ECU swap along w/ all the other bolt ons. His car is fast on the quarter mile, but at the sacrifice of bottom end power.

Once you establish this, then you're on the right track.

Larry

 

I was under the impression that a lightweight flywheel, while great for autocross and street driving may hinder his launch at the track