I have a question about removing my cat from my L98 TPI. I was wondering if I would lose some torque/hp or gain anything maybe mpg. I have a friend who did it on his 94 Z28 and he says its a little doggy on take off but any suggestions or comments will help me decide. Probably going to do it this Friday.

 

Should be gains, unless you put on a test pipe thats smaller than the rest of the exhuast system.

 

Unless it is a race car, just keep it on.

 

 

Like I said, unless it is a race car, there isn't much need to remove or gut it.

A normal street car driver isn't really going to need to gut a cat to gain a few HP. Cats, especially modern hi-po ones, are not that restrictive. A performance car can see a heck of a lot more in the way of gains by performing mods that don't make the car a gross polluter and give the hobby a bad name. Cam swaps, gear swaps, ignition upgrades, exhaust upgrades, intake upgrades are all gonna get you to a healthy power level while keeping a cat, stock or otherwise, on the vehicle.

Now, to reiterate, if this is a killer race car for strip use, then it's a different story.

Maybe my current position is a function of age. 10 years ago, I wouldn't have thought twice about pulling a cat, but now, I actually think the next time my GTO gets a new exhaust (years from now) I'll throw a pair of high-flows cats on there.

 

Environment. On a mild setup (such as stock anything), having no cat may yield a couple horses. The smog isn't worth it. Some people want the smog for the couple horses, some don't. I plan to use a new cat when installing full exhuast.

 

Hi-Flow Cat is the way to go

 

Another vote for a high flow cat. Bull summed it up well. On a stock system not much is gained by removing the cat. That is unless it is clogged. You see gains when you upgrade to mandrel bent pipes that are larger in diameter than stock. The cat alone is a tiny portion of the restriction of the stock set-up. Today's high flow cats do not rob power when properly matched/sized. They tone the exhaust down and keep the guy driving behind you from passing out. Not to mention that they are very cost effective.

 

a cat is $80+
a straight pipe is $8 Simple math for me. That is if there's nothing there, and you need to put *something* in. If it already has a high flow cat, leave it.

Lack of a cat makes the car sound more grumbly, the cat acts as a resonator usually. Also, a well tuned carb, or FI car makes very little smog compared to the big old boats of the '70s when cats were needed. Your car will smell a bit more like a boat though

I chopped it off my last car, and this car the PO said he hollowed it out, I looked, and sure enough, it's a pipe, so i'm not going to touch it. my

 

Please do a search on this topic. It gets posted at least twice a week.

Having said that, removing your cat is a federal offense, punishable by a $10,000 fine and/or jailtime if you get caught.

Third, if I can make 300+ HP to the wheels, run 12's in the quarter, and pass a CA smog test with dual Magnaflow cats, so can you.

 

After I gutted my cat, the exhaust was a lot louder/deeper and it crackled when I let off the throttle at high rpm's. Probably gained a few hp and better mpg b/c it was clogged.

 

oh yea, if it's illegal where you live it's a *bad* idea to remove it. Up here in r*dneck land, it's no big deal at all.