CAT Mod.

[navdoc101]

Gettin' ready to do the CAT mod. What has everyone used to mod the cat? What tool/ bar, etc.?

[DriverOne]

Generally, a scalpel, pair of snips, some sedative, and a $100 vet bill...

[Grey Vw]

Never heard of this CAT mod..

[htchbck]

I've seen folks use a flex pipe and put the old cat shell back around it... since the shell easily comes off with 6 studs/nuts.

[blkfordsedan]

I generally advise against "gutting" a cat (converter, that is). The reason is that exhaust gas velocity is extremely important to engine performance. If you hollow out the cat body, you're left with a large open chamber that will create flow turbulence. The expansion of the exhaust gas upon entering the large open chamber will greatly reduce the flow velocity. Usually, this results in a sizable loss in low RPM torque and reduced MPG. The exception to this would be if the cat is actually plugged to the point of causing issues....in which case, gutting it would actually be an improvement. I would either replace the cat completely with a piece of pipe, or maybe install a length of straight pipe through the center of the cat body. In most cases, the connection flanges of the cat are very rusty and weak anyway and tend to crumble when removed. I think replacing the entire cat with a piece of pipe and a flexible joint would be the best option. Just my 2 cents....

[Grey Vw]

Oh...gut the cat. Just make a pipe that will fit the original location and put the cover over it.

[navdoc101]

Okay, thanks all. Pipe it is, no guttin', converter that is.:eeeeeek: I don't need a seditive , just a beer.

[Pu241]

Actually, you could scrap the cat for good money, used to get $80+ for them last year.
Would pay for the pipe swap and maybe then some.

[Christ]

Replace it with a resonator, scrap it, put the heat shield back on.

[Christ]

P.s. Most modern cats flow sufficiently to not create unnecesary restriction. Just throwin' that out there

[zoom zoom]

I've been told that if you weld a washer inside the pipe after deleting the cat it will create enough backpressure to not do any harm, but still be open, and isn't as loud when your just cruising until you step on it. I haven't personally tried it, yet.

[navdoc101]

P.s. Most modern cats flow sufficiently to not create unnecesary restriction. Just throwin' that out there

Its 18 yrs old. probely a little restricted.

[TominMO]

I have used a drill, an 18" extension for a drill bit, and a hole saw in the past.

[Tex Law]

Gut The Cat

Gutted mine out with a piece of rebar, welded in a piece of exhaust tubing...looks like a cat (required here), but it's open all the way back to the muffler.

[Christ]

Its 18 yrs old. probely a little restricted.

Ironically, if it's restricted at all, it's not functional.

Theyll generally flow as well 20 years later as they did from day one. If it's getting plugged, theres a problem elsewhere that needs to be addressed.