hollowing out cats

[still.popimpin]

hollowing out cats DONE ! maybe another problem ???

I am going to hollow out my cats. I am thinking about just cutting a square out of the bottom of them, hollowing them out and welding them back together. what do you guys think? I was gonna just cut them off and replace them with 2 pieces of flexible exhaust hose, but think it would be a little easier, if not more reliable to just hollow out the cats. Are the cats pretty much a str8 shot? (my car isnt here right now to look) if so, could i just cut them off real close and replace them with a piece of str8 tubing?

 

[RacingNotPacing]

Are the cats pretty much a str8 shot? (my car isnt here right now to look) if so, could i just cut them off real close and replace them with a piece of str8 tubing?

not really, I know the one cat has the down tube come strait into the top of it, making a 90*right in the cat.

If i can find a pic I'll post it up here.

 

[1993MTXSHO]

I did it, I have a shoshop highflow y pipe and I cut a hole in them right around them seam and welded it back together it doesn't fully look like it was cut open so if a cop looks I have cats. I haven't had any issues yet apart form low end torque loss and its a little louder. I gained some top end though

 

[still.popimpin]

hollowed them out today, been a while since i ran a welder though, got a couple small leaks, gotta fix them. questions though, you said something about lost low end torque. how much? is it noticeable? Mine is, and it is kind of worrrying me, almost seems like a miss, and since i can hear it pretty good out the holes i didnt weld good enough on the cats, i get a weird hiss type of sound, not really a hiss, more of a pffsst !!! if that makes any since. only does it once around 4 or 5 grand. pulled codes before i hollowed the cats and got 22 ????? Tryed it running and got 333, thought that was odd. any help

 

[Colin95MTX]

What I do on a couple of my cars without cats that require them, is cut old clogged cats in half from any car, gut them, then weld the casing around some straight portion of the exhaust...doesn't solve your original cat gutting question, but it does solve my passing inspection problem. Much cheaper than ruining good cats, good cats, even used old old old ones are worth good money at junk yards. I get anywhere from 30-120 bucks per cat at my local yard.