My car has been running poorly of late, I was told that the cat may be clogged. I am going to buy a Random Tech cat eventully, but with the cam I just purchased, finances are a little tight currently, so I am going to just gut the cat and slide a piece of 3 inch pipe on the inside. My questions are:

How do I get the cat separated from the AIR, do I have to cut it, if so, will not having AIR negitively effect anything?

When I slide a new piece of 3 inch pipe inside of it, will cooling the pipe (i.e. setting it in the freezer for a few hours) shrink it enough that it can just slide in?

How will the car sound AND perform after this?



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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: LT4 Hot Cam, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

 

Yep, you pretty much have to cut the air tube. You can get high temp silicon hose to reconnect it. Its expensive (like $10-12/ft), but it works. As far as sound and perf. I gutted mine but didn't put a pipe through (have dual cats). I think my perf. actually suffered a little (esp. low end), probably because of the funky pressure waves set up in the big empty cats as the exhaust expands in the cat body, then has to get out the exit. As far as sound it made mine quite a bit louder and throatier. I would suggest running the pipe through it like you are talking. I have a Hooker aerochamber muffler.

 

I've successfully gutted four cats using a pipe just big enough to slip through the nipples. I use a piece of cast pipe ground down on one end to a razor-sharp edge and a cap screwed into the other end for turning and pounding. I go in from one end until I hit the AIR pipe, then come in from the other end. Then I cut out the AIR tube so that it's not sticking into the exhaust stream but will still allow the smog pump to do its thing and maintain appearances.

 

Thanks guys, this sounds like its pretty easy.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: LT4 Hot Cam, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)