Catalytic Converter Face-Off

good to see that the Magnaflow universal is so good. I need a cat for my Saab, so I think that is the way to go over the original

In reply to mad_machine :

Just bear in mind that the spun universal is single wall construction, so there's no heat shield to protect the vicinity from heat, possibly red hot with a cat failure. The shell is heavy enough gauge to weld on some studs to mount a shield to protect whatever's too close. As a previous poster noted, you can get the housing with an angled outlet that helps a lot with system layout.

In reply to Spoolpigeon :

I sent my stock S2000 cat to Random Technologies for them to test to see which cat they had that would flow better.  The stock S2000 cat flowed better than Random's 3" cat.  Because of this they began offering the 4" cat.  After seeing that I elected to keep my stock cat.

Also I've seen about 125 dyno pulls on various S2000 configurations and a few other Hondas and every time the power bands were much smoother with the cat than without.  I'm going to run a cat on the race car I'm building.

I'm putting a cat on my Ford Model A hot rod and you can't stop me!

i had a mazda rx/7 turbo2 that i ordered a cat-back for from a major supplier, about 20 years ago.  instead, i received a long pipe with a phony "cat box" where the cat should've been.  it released so much power that the fuel pump couldn't keep up:  i couldn't get within about 700rpm of the redline, let alone set off the buzzer!  mileage went up too.  heckuva deal!

In reply to irish44j :

raspy garbage can be easily corrected by a turbo install ....lol

I wouldn't mind my car smelling a bit better. It's tuned fairly well so that in most cases it isn't offensive, even to open top cars behind me, but an improvement would still be nice.

However, I think anti-lag and two step shenanigans would be blowing substrate components out the back at a fairly regular intervals...

Great article, I've been trying to tell everyone not to run test pipes and how its not worth it. Now I have proof! Without cats, exhaust stinks (cause its full of poison) and is raspy. I've been using the Magnaflow universal cats for a long time and they are cheap, easy to fit anywhere and don't take hardly any power away.. 

te72 said:

However, I think anti-lag and two step shenanigans would be blowing substrate components out the back at a fairly regular intervals...

Yeah, those would be kinda bad for a cat.  There might be some metal substrate (instead of ceramic) cats that would hold up better to the abuse if you shop around.  Or rig up a setup with cutouts to bypass (and block off the inlet of) the cats for when you're using those features.  

rslifkin said:

te72 said:

However, I think anti-lag and two step shenanigans would be blowing substrate components out the back at a fairly regular intervals...

Yeah, those would be kinda bad for a cat.  There might be some metal substrate (instead of ceramic) cats that would hold up better to the abuse if you shop around.  Or rig up a setup with cutouts to bypass (and block off the inlet of) the cats for when you're using those features.  

Interesting you say cutouts, plural. At first, I thought you meant only one, which, on my setup, would likely have me being politely asked to leave due to noise levels at some tracks... However, with two cutouts... That's an interesting idea.

Alternatively, I could run one exhaust setup strictly for street and road trip use, and another catless setup for track use. Thanks for the suggestion!

In reply to te72 :

Yeah, the thought was 2 cutouts.  1 controlling flow through the cat bypass pipe, the other controlling flow through the cat itself with the 2 pipes merging back together after the cat.  To switch the cat out of the system, you open the bypass cutout and close the cat cutout.  

In reply to rslifkin :

Would basically be the same idea, plumbing wise, as recirculating an external wastegate. Not a big deal if you can find room for 3" pipe plus the cutouts... combine that with my desire to build a flat floor for the car, and well... probably not gonna happen. Do appreciate the suggestion though!

Flyin Miata makes a downpipe with a cat for my car now that is street legal.  Costs less than half what the one I would otherwise have had to use does too, so double bonus.

My 88 TBI 350 Silverado still has the original exhaust. Tail pipe is rusted through at the end, so I've been thinking about a replacement. 

Seems to make sense to look at changing it from the manifolds back (the Y-pipe is said to be very restricting). 

Depends on the car and on the cat.  On my old VW Mk2 16v GTI, there was no power to be had by going with the Euro downpipe, although you did gain some torque.  On my 944 Turbo, definite power gains by losing the cat.  On my E36 M3, 10-12rwhp by dropping the cats.

Even on the latter two cars tho, the power gains aren't so much that I'd remove the cats on a street car, only on a race prepped car...

Zombie cat revival

Bumping because the data table picture seems to be broken.

I noticed that as well.

Interesting. I hadn't noticed this thread the first time around.

Some cars (like my Solstice GXP) are set by tune to a preset intake volume/torque output so unless you get e retune, it doesn't matter what CAT you stick on the car, you'll get the same output.

WITH a retune you pick up 16-18 bhp from the new CAT; without, all you get is bragging rights when you lie to your friends about how much power you now have.

In reply to flatlander937 :

Yeah, they got rid of the flanges on that configuration.

Kook's Headers and Exhaust also makes a high quality line of free flow and 49 state EPA approved cats.  Don't know how extensive their applications are but I am running a pair of Kook's 49-state EPA stainless cats with Kook's headers on my Camaro SS' Borla cat-back and, the Camaro likes.

Would like to see the same test on say a 400-500+ HP car. I have never  dynoed our 96 Supra with the cats on it but on the drag strip cats slow the car by over 1 second and that's way more than 1 or 2 horsepower.....and KILLS turbo spool :)  When dealing with 100 HP car I am sure not much kills power.