Sentinelist

I'm looking to remove the catalytic converter on my 951 soon. For, ermm, off road purposes. Tips and suggestions on what specific pipe to replace it with? Didn't find a lot in the search- thanks.

aben8057

Hey Chris,

What I did was to weld a straight pipe from the factory cat all the way through. Then I bought a high flow cat and 2 band clamps. Therefore, when I have a track event, I substitute the cat for a straight pipe and when I have to pass emissions, in goes the cat.

odurandina

1. delete the cat.

2. install a test pipe. car won't become too loud.

BlackOp

http://www.pelicanparts.com/cgi-bin/...0%281986-88%29

This is what I'm going to do..that way I can keep the Cat in tact..you know, in case the lawman gives me any trouble.

Reimu

Here we have visual inspections for the cat

So I replaced mine with a glasspack

Van

I would by a test pipe from Lindsey, then buy one from Fabspeed, then buy one from SFR, then I'd cut out the old cat, weld in a pipe that's 2.5" diameter, and, finally, sell the 3 test pipes on Rennlist!

Sentinelist

That's what I'm looking for, and have the same thought. I had a test pipe on an old Passat that worked great- I do intend to hang onto the cat just in case (it's still good, but cars older than 25 years in Texas no longer go through emissions tests).

Is the OE cat welded on there or can I unbolt the thing and DIY with a wrench? I haven't jacked it up to take a look at this specifically.

Van

The cat is welded in place. The pipe is double-wall in front of the cat - down pipe and S bend - for better insulation. There's also a secondary, tiny cat on the wastegate bypass pipe.

Sentinelist

Bugger. Ok good to know, thanks.

Jamesr6967

What we used to do in my younger years was remove the cat, split in half and gut it, then weld a pipe through the center. Basically just put the shell over a length of pipe. Looked just like it had a Cat for the visual inspection and oddly enough, it still passed the 'sniffer test'.

Sentinelist

I've heard of that method- that test pipe I bought for my old Passat looked identical to the OE cat for that purpose. What was nice about it was, IT BOLTED ON. I'm not jazzed about this welding malarkey. Especially since I've had to get my indy to spot weld a couple leaks in the system already.

Jamesr6967

I believe some of the cats we did had bolt on flanges welded to them which we duplicated when we put in dummy cat. No worry of leaks because shell was simply welded over the pipe.

Jamesr6967

I think I like the idea of using band clamps. Have an exhaust shop expand the pipe(s) to create a male/female joint and wrap a stainless steel band clamp around the joint.

LuigiVampa

+1 - This is generally how I replace most components on my car.

But in all seriousness, is there any benefit to welding in the 2.5 inch pipe inside the cat? Can't you just hollow it out?

Mangonesailor

I believe you can just hollow it out. Anyone with a few wrenches, a broom and a shop-vac could do it.

I should probably do this next weekend too.