I'm trying to replace my cat with a straight pipe. I've got two questions:

1. My cat is welded on- how what do I use to cut it off?

2. How should I put the straight pipe on and shat size whould I use?

Sorry, I've never done exhaust before.

Oh yeah, and I've got a 85 Z28 305 bbl.

go to sears and buy a pipe cutter. it will either look like a chain with a handle or a c shaped tool with a blade in it. then just cut the pipe and weld on the new pipe. if you dont want to buy the cutting tool and have a grinder just buy a grinding disc and cut it off that way just be careful not to cut through the floorboard.

umm......

One word...SAWZALL!

sawzall would be my #1 choice
grinding wheel 2nd
i have done it with a "heavy duty" cutoff wheel on my dremel.. took awhile, but was still better then a hacksaw
you could try a pipe cutter.. athough the clamp type probly wont fit between the floorboard and pipe... the chain type could work, but ive never used one personally...
theres always the hacksaw

go to a parts store and rent a cutter. wont cost u a dime. i cut both cats off recently with it. only drawback is it wont be as quick,,,but hey,,,it's free.

i like the chain style pipe cutter mentioned above

if you know how to use it right it will cut the pipe in 10 seconds

i use one at work all the time for exhausts and it really is quicker than using a grinder

Me and my cousin dropped my exhaust to bash out the kittys guts... since my bolts have basically welded themselves on, we used a hacksaw... while the exhaust was still on the car. THAT was an 'entertaining' experience, lol

Its not too hard really with a hacksaw, just that once you get to about 1/4" from the top of the pipe, you will have to have someone force the pipe down to get the saw to reach that top 1/4". The way me and my cousin did it was that one of us put a crowbar between the body and exhaust and pushed down, and the other cut the last bit of pipe. This was the L69 exhaust BTW, and the car was lifted about 6" off the ground in front.

BTW... gutting your cat like I did can give it a nice burbly rumble that i guess the cat used to absorb... its nice

Seems to have a little more ***** at the really top end now too, but only enough to just make it noticeable.

sawzalls work great.....and they are very well the coolest tools on earth

I always used a reciprocating saw.