redliner8

iTrader: (1)

Does anyone have a recommendation for a high flow catalytic converter that will work with our cars, preferably metal core? I'm having trouble finding one that would be direct bolt-on. Someone mentioned Tom's on a different thread but I'd rather stick to something affordable if possible. Thanks!

GilfHunter

I Guess not lol im sill looking for mods for this engine

AVSRacing

I doubt there's gonna be anything bolt on, probably gonna have to weld on or custom fab. Do you have headers and full exhaust? I doubt you'll get much power from just doing the cats.

joemg

the stock cats will flow way more than you're going to make on this car. They're not even restrictive on small supercharger applications. I wrote up a thread with all the math a long time ago, its on here somewhere. TL;DR delete the middle cat and keep the 2 front originals.

add to that... keep the front Y pipe for the same reason. I learned that lesson the hard way on the dyno. Just replace the mid cat with a resonator and do whatever you want from that point back.

AVSRacing

Where's the mid cat? Isn't it just the 2 cats into the y pipe? And a resonator in the middle?

joemg

the 3rd cat is in the y pipe. Most people cut it off and replace with a resonator.

there’s only 2 o2 sensors after the first 2 cats, not after the 3rd

AVSRacing

^^ what Dyno results did you get? I wonder if just cutting out the 3rd cat and replace with straight pipe will yield any results? Louder exhaust? I've always thought that was a resonator.

joemg

Around 250whp/250wtq. I have headers, Y-back exhaust, Honed intake manifold, Aristo LSD, and All4swap/Quantum ECU re-tune.


Chasing naturally aspirated power on this engine is kind of a fool's errand (ask me how I know), but I do love the results I got.


Removing it with a straight pipe might be a pinch louder. These engines are really quiet, even with out a mufflers or a dump pipe they're pretty quiet cars.

Raven01750

Is your car still Registered in CA Joe? Long time buddy. Glad to see you back for awhile.

Paul

joemg

Hey Paul! Sorry, i've been busy, lol. Glad to see you're still on here.


Actually, no, I recently switched it out of state.

Raven01750

You Rat Bastard! I was wondering how long you were going to be able to get away with all of those mods here in Cali. Did you swap out your LSD for a different one? Different gear ratio?

Paul

joemg

HAHA, yeah, it was becoming too much of a hassle.

Here's my LSD swap thread from a while back:
https://www.clublexus.com/forums/sc4...l#post10626176

Same 3.76 ratio, because I have an 06+ I had to swap the half-shafts from the 02-05 SC430 to match the splines on the Aristo (or Supra TT Auto) differential.

I believe if your'e swapping into a 02-05 the OEM ratio might be different than 3.76. I think it was lower.

Also, there are 4.10 and 4.27 gears you can swap in from various supra variations. I chose not to, though it would have been LOTS of fun, because your mpg will be impacted strongly.


sorry to go off-topic, but that thread is very long, so I gave you the tl;dr.

Julesnfl2

Question if I hollow out the first 2 cats or cut the flanges off two and put straight pipe and put them in will it mess with the motor or will it just throw a check engine light but run fine?

joemg

a straight pipe will only reduce torque, throw a code, and smell like ****. Not sure if it goes into limp mode.

our cats flow far more air than any n/a bolt-ons would require.

however, if you’re hell bent on it, Megan racing makes resonated straight pipes that bolt onto the stock flanges so you can go back to the original cats if you decide you don’t like it.

Julesnfl2

ok thanks for the info. The reason I ask is because I bought some off of rock auto (that I’m going to send back) that have fell apart in the middle causing a rattle in my exhaust and a check engine light. I bought one set before these ones just to get buy while between jobs and they did the same thing so I spent a lot more on the pair that are in now but they did the same thing cause I am getting the same exhaust sound as before. It’s been about 6 months since I replaced them last. Only reason I replaced the first set is cause the stock ones looked old and I was doing the y-pipe back so I figured I would replace them also.