Found this looking around on the internet. This guy has a 355, LT4 Hot Cam, and a SuperRam with Trickflow heads and he did a comparison on his car. Go info...no cats didn't make a big difference at all...only 1 hp and a few ft pounds of tq.

http://dtcc.cz28.com/gta/dyno.htm

 

Sounds about right. I wonder if he used a test pipe, or just used an empty cat.


I bet the gains would be even greater if he was using the stock cat.

 

Modern day cats are no longer a bottle neck in a properly sized exhaust. That is why there is no reason not to run one (on a car that came with them to begin with).

 

VincentZ28 has been running at the track with no cats. He had to get his car smogged and left the dual cats on. Guess what? He had a new best et.

 

Well it said a GM 3" cat so...I think it would be pretty much stock.

 

That is my dyno test referred to on the website. The test used a 3" in/out factory GM cat from a 95 GM pickup truck. For the no-cat test I installed a test pipe.

 

That's good info because I was wondering how much it makes a difference. I am going to switch from one cat to 2 high flow cats coming up and I don't have emissions so...its all good.

 

I wouldn't bother honestly. If one only takes away 1HP and less than a handful of ft-lbs of torque, why spend double the money and buy two of them? I'd just stick to a single one...unless you're going true duals all the way back.

 

b/c i have two carsound cats already that my father wasn't going to use anymore so I am going to put them to use!! But i might gowithout them...don't know yet..but leaning more towards putting them on.

 

Remember not to only look at peak power, throughout the powerband it was worth a constant 5 hp and about the same torque.

 

Yea, but the point is...it didn't take away much with a stock cat that wasn't a high flow unit.

 

I see what your saying. But I think it is different when your dealing with a 15 + year old cat (in thirdgens atleast).

 

No doubt...but a 95 cat is now 10 yrs old still. I have 1990 truck so its even old. I replaced it 6 years ago with a high flow unit from Catco but those flow teh same numbers as the new cats from GM. Now a high flow unit from carsound or random technology and you will pull the same numbers or more and be emission safe. But good points though all around.