dropkick_muppet

iTrader: (4)

if anyone is interested, here is the response i got from xcceleration.com when i emailed them about their cat'd up/down/mid pipes (all caps is theirs, not mine)

Subject: subaru WRX high-flow cat'd up and down pipes

hi, i've got a couple of questions about the high flow cat equiped up,
down, and mid exhaust pipes that you offer for the subaru wrx.

1) do they bolt up to stock parts?YES for example, will the cat equiped
downpipe bolt to the stock midpipe or would i have to replace both stock
pieces? YOU DON'T HAVE TO RELACE ADDITIONAL PIECES. EACH PIECE OF OUR
EXHAUST SYSTEM IS A DIRECT REPLACEMENT FOR THE OEM COUNTERPART.

2) do you have dyno charts available for the parts? WE DO NOT HAVE DYNO
TESTS OUR SELVES. RANDOM TECH WHO MAKES THE PIPES FOR US HAVE DONE NUMBEROUS
TESTING ON ALL THEIR PRODUCTS THEY HAVE SAID: Our cats are made for us by
Random Tech. The following is from their website on the cats:

Dyno testing has proven that to be true. According to engine builder Mike
Osucha, (MORE Performance, Charlotte, NC) "We recently built a 396-cubic
inch LT1 engine that produced 455 horsepower with an open exhaust system.
When we installed two Random Tech converters, the engine produced 458
horsepower. When you look at the complete test results, you see that at some
points the engine makes more power without converters than with them. And
vice versa. I think the bottom line is that there's a tuning effect when a
slight restriction is placed in an exhaust system. But the real point is
that with the right catalytic converters, you don't have to sacrifice any
horsepower to make an engine emissions legal."

So you can see, with the metallic cats, there should be little or no
difference. This is where we got the text:
http://www.randomtechnology.com/technical.html


3) do the pipes have provisions to accept stock 02 and EGT sensors? YES THEY
DO

4) do the aftermarket cats cause a Cat inefficiency code check engine
light, or any other CEL? IF YOU ARE RUNNING THE DOWNPIPE W/CAT AND MIDPIPE
W/CAT THE CEL SHOULD NOT COME ON.

5) will the up and down pipes help the turbo spool up faster, and
produce more torque/hp at lower RPMs?
THE WHOLE TURBOBACK EXHAUST SYSTEM
WILL PRODUCE MAX. TORQUE AND HP BECAUSE OF IT'S DESIGN. IT IS A 3" DESIGN
FROM ONE END TO THE OTHER, WITH THE LEAST AMOUNT OF BENDS AND USING METALLIC
CATS WHICH FLOW OVER 500 CFM OF AIR. THIS MAKE S THE SYSTEM PRODUCE THE
LEAST AMOUNT OF BACK PRESSURE AS POSSIBLE. THE CONCEPT COMES FROM HEATING
AND COOLING ENGINEERING. HOPE THIS HELPS.

so i think i'm going to go with their cat'd downpipe, the OEM mid pipe, and a catless up-pipe. that'll give me two cat's in the system so that i should pass emissions without any problems. the only pipe without a cat won't be visible, and i'll eliminate the potential for the up-pipe cat to break apart and fly into the turbo. depending on how the parts work, i may opt to go with their cat'd mid-pipe at a later date. once i get everything installed, i'm going to try and find a shop with an AWD dyno, and get some hard numbers, which i'll be sure to post here. thanks to everyone for their help.

bone324

Dyno is a good idea. But, to be sure you get good data, you should get a baseline dyno done. If you don't know what you started with, you won't have an accurate idea of what you gained. I would recommend unplugging the battery at the dyno shop and clearing the ECU by stepping on the brake to get all the juice out of the system before the baseline and final dyno pulls. That should give you an EXACT number for gains.

dropkick_muppet

iTrader: (4)

absolutely. a baseline dyno run is definitely part of the plan. basically, my thought was that i'd find a shop arround here that i trust with an AWD drive dyno and make a couple of runs with the motor the way it is now, and then make subsequent runs after i make engine modifications. i'd be doing all the runs on the same dyno, so that the before/after comparisons would be accurate.
my engine experience is mostly with motorcycles, and it's pretty standard to make three dyno pulls to get one reading. dynos are so sensative to the operator and environment that getting a good accurate run takes quite a bit of effort. i've seen three back to back runs yield differances up to 3-5hp. hell, just a change in ambient temperature and humidity can change your readings enough to make you wonder if the parts you just put in make less hp than the stockers!
just out of curiosity, why should i reset the ecu before each pull?