I am thinking of removing the cat. Is this going to be a good thing or a bad thing? I heard that I will be loosing backpressure.

 

i removed mine lastyear on a 86 305 tpi ,,terrible gas milage put the cat back on and got way better gas milage,,, also you loose a little off the line

 

As far as backpressure goes i dont know,but i can tell you that after removing mine i noticed no difference in power or anything.(I removed mine cause it was bad and sounded like rocks in a tin can being shaken up)

 

Neither of those makes sense to me...

 

good.
Back pressure? So I guess that's why so many race cars don't have any exhaust. They don't want to go fast. Or maybe they just don't like the loud noises.

Why do you swap manifolds for headers?
Why do you put on a cat back w/ a less restrictive muffler and bigger pipes?

FOR LESS BACK PRESSURE
There was a great technical article that broke everything down and explained how backpressure is bad and why people think that you can have too little of it. I wish I could find it, but yet again, the search isn't working.

ANYWHO, if you want some gains, gut the cat or take it off. Or even replace it w/ a high flow unit if you want to stay emissions friendly. There's vertually no difference in power between a highflow cat and no cat. But the stock cat does choke it up.

 

Right it's one of those things that you KNOW is helping whether or not you can FEEL it.

 

just gut it. i've done it on every f-body i've had and it hasn't stopped me from passing inspection. the car has always run as good or better.- although maybe a little louder.

 

A gutted main cat isn't a good idea unless you put a straight pipe through it. The sudden loss of velocity hurts high end flow, though it does help exhaust scavenging for low RPM torque production... There are better ways without trading off so much on the top end...

 

for the little bit of power you lose, im 100 times happier with it on. i think its a dumb idea to take it off honestly. first off there are laws for a reason. second, its nice to breath some decent air once in a while and third, id never pass inspection without it.

dont see why you would take it off for the ~6hp you gain.

 

One problem you may run into...EGR system works off of exhaust backpressure. Too little exhaust backpressure will result in a low EGR flow, which can cause high combustion chamber temperatures and detonation.

Darrell