smacko

Does anyone have pro/con thoughts or experiances in 'gutting' the Catalytic convertor (i.e., smasjing the interior out and leaving just the empty housing there) I KNOW it is 'naughty' in the eyes of the law, but have mixed stories of cat convertors robbing power, not working after xxxmiles anyway etc.

Any thoughts?

LaVidaLoca

Did mine, BUT there is no smog inspection here. (or safety for that matter).

Just broke up the material with a sharp punch and removed it. Runs a little louder now. Welded up the air fitting also.

Everything works just fine.

smacko

Thanks for the speedy reply!
Any noticable difference to performance etc?

BAM92

I bought a second set for "gutting". Will switch them out when time comes for inspections. I figure I will use quality bolts so switching them will be easier.

smacko

We don't have annual inspections in my part of this small planet.
Good idea tho; do you notice any difference between the two?
What about the air pump line - block it?

buzzbomb

I put a plug in a piece of hose to block the air pump line. I also used a spade bit and an electric drill to do the gutting, works great. I noticed a slight increase in noise, and an occassional quiet backfire on deceleration. On the performance side, I noticed a big difference in performance, but mine was pretty plugged up, my gas mileage incraesed by 4 mpg! :cheers:

bac22

Only problem with gutting the cat is you create turbulance in the cat which impedes exhaust flow since you are going from the small intake manifold pipe to a wide open space. I've yet to see a car make more power on a dyno with the cat being gutted. Of course if you cat is clogged, the STP feeling will feel like you have gain more power, of course that makes sense if you think about it.

People who have do say they have HP gains probably get them because most people will upgrade the exhaust system with a better flowing exhaust system at the same time they gut the cats.



[Modified by bac22, 7:19 PM 8/5/2003]

smacko

Thanks for your reply.
So I'd be better to weld a pipe (Hidden inside the gutted cat) from one side to the other to make it a straight thru system...

bac22

Yup, that is the best thing to do, or just replace the cat with a straight pipe. You may be able to get a custom exhaust shop to provide one. Of course putting a striaght pipe actually in a cat would let you pass the visual inspection if you ever came across one.

A lot people forget that while towns and/or states may not have emissions, removing a cat is breaking federal laws.

steve40th

GM makes a cat bypass pipe for LT-1's ready to bolt in. They use them for oveseas cars where unleaded is unavailable. Of course to run your O2's you will need to have some bungs welded in. Steve