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Old 06-03-2002, 06:27 PM   #1
Red Rocket
Scooby Specialist
Member#: 10507
Join Date: Sep 2001
'04 Ex STi Owner
'97 4Runner

Default Stock 3rd cat vs. high flow cat?

I'm thinking about doing a Scooby Sport downpipe and leaving the stock third cat in place. An uppipe is going in at the same time. The 3rd cat is actually rather small, I think the wide part of it is only about 4" long - pretty minimalist actually. Has anybody had a look inside at the catylitic element? Any thoughts on how this might compare to a "basic" high flow cat on systems such as the BPM or Turbo XS?

I currently have a ''custom" el-cheepo (2.5" crush bent aluminized+Dynomax Bullet muffler) cat back that I've had for a while and will run a little longer. Not optimal by a long shot, but less restrictive than stock. Soon I will have at least a custom stainless muffler section made up with a Waker Dynomax muffler to run with the stock mid-back pipe and then eventually get a Scooby Sport midpipe.


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Last edited by Red Rocket; 06-03-2002 at 06:39 PM.
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Old 06-03-2002, 09:04 PM   #2
Scooby Specialist
Member#: 15451
Join Date: Feb 2002
Chapter/Region: MWSOC
Location: Lewis Center, OH USA
2016 Accord EXL Navi
Lunar Silver

Wink Here's my gist

After many late night hours reading, and learning about this engine, and it's quirkiness, I ended up with the following (exhaust components):

ATR up-pipe
Stromung catless downpipe
Stromung twin tip SS muffler (back box as the brits call it)

I know the Stromung down is still a "tongue" design like OE, but it really is impressive (bell mouth might be better, but more $$$.) I've got a few other goodies to help:

K&N panel filter
Intake resonator hack
Samco IC hoses
STI hood scoop*
Quantum Racing air splitter*
3/16" restrictor mod
Forge 100% atmo BOV
4 point grounding mod
Mobil1 10w30

All these really make a strong runner, all on the stock ECU tuning.
I do want better engine management, but haven't decided which route to go as of yet (there's more HP/torque to be had with tuning, that's a fact.) Before I tune the ECU, an IC upgrade may happen (trying to make a really good buy in the not too distant future.)

Fact of the matter is, the OE 3rd cat is very small. It's make-up looks as good as I've seen (can't really judge much on this, only remember seeing a Catco high flow converter some time ago.)

The car is on the verge of being too loud for my tastes now, so the OE 3rd cat stays. Might swap the mid with a Stromung, but that's it for exhaust till I need a set of headers!!

For what it's worth, HTH.


*install coming next week.

Edit: Just to let you know, I did the o2 CEL/MIL fix from www.ponyexpressperformance.com as well. Works like a champ!

Last edited by MackDaddy; 06-03-2002 at 09:10 PM.
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