My RT is giving me chronic CELs too. I still have the offroad bung on my Buschur turboback, so I'm going to try that to see if that solves the problem.

 

Are U guys getting the PO420 code with these Cats?

 

My but dyno as well as my gear selection in tight corners indicates that the test pipe makes a huge difference. I get considerably earlier spool and what feels like more power. I am sure it broadens out the entire curve!

Vishnu Sig with high flow compared to test pipe.

 

This solution works great and is cheap. No CEL with the test pipe!

https://www.evolutionm.net/forums/sh...ad.php?t=98573

 

I had the high flo cat and when I removed it the car made 15whp more...big differance mostly in 5k plus range

 

If the CAT is emissions compliant, it will rob a significant amount of hp, depending on mods. If it is a legit high flow cat, you will still loose a measurable amount of hp. If the CAT is a phoney baloney CAT that is actually almost like a test pipe (exhaust does not actually run through CAT screens/material, but past them) it will loose no power.

 

if u want you could go with the qtp cutout, but ive heard mixed reviews about it

 

Hi,

Just as a word of advice, if you're buying high flow cats, make sure you guys are getting the metal substrate ones. Metal substrate cats are head and shoulders above their ceramic counterparts in terms of durability, superior flow, and cleaner emissions. Also ask for a cell count on the cat. If you're purchasing over a 300 cell count cat (cpi), you might as well keep the stocker. If it's under 150 cell count, you may want to see if it will pass emissions in your area.

Cheers,

Gary
Gruppe-S

 

Okay, turns out that my O2 sensor was loose. So, now just back to occasional CELs.

For you guys that got big HP gains after losing the cat, what cat were you using before? The Buschur cat is a poor example of a high flow cat, so that shouldn't be the yardstick.

Also, after doing research, I agree with Gruppe-S about the metallic substrate cats. That's what I have. Be careful as Random still sells ceramic cats too and their website (last time I checked) had incorrect information about their best flowing cats. I verified this after talking to them on the telephone. On my car, I had a 3" Random metallic substrate welded into my Buschur testpipe so that I could use it with my Buschur slip-fit turboback.

 

Good info Gary. Do our stock cats use metal or ceramic substrate cores?

 

Yep. I pm'd Al way back when I was deciding how to finish out my exhaust. He claimed a negligible gain with the testpipe over the HF cat. Since I already had an UR cat-back, I got their HF with the downpipe to finish it out.

It's also nice to be legal, not killing the ozone layer, not overly loud, and not having that rotten egg smell!

I say HF.