Adding high flow cats to off-road prochamber
04-05-2016, 09:33 PM
#1
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Location: Nor Cali
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Adding high flow cats to off-road prochamber?
Hey everyone! I used to run an off-road prochamber for 6 years when my car was brand new until I had to put my stock catted mid-pipe back on for smog purposes a few years back. I'm currently running a Pypes x-pipe with Borla Stingers and this setup sounds good but I want it louder. I want to put my off-road prochamber back on and I have this idea of adding high flow cats to the flat area of the down-pipes (see picture). This should increase the exhaust volume and also eliminate the exhaust smell which I didn't care for. I plan to use my 91 Street tune again. It was made for the off-road prochamber and it turns off the rear O2 sensors. I figured I would use this tune instead of my 91 Smog tune because the high flow cats don't have O2 sensor bungs anyway. Would there be any problems with this setup? I'm basically going to run an off-road tune and the HF cats are just there to eliminate the exhaust smell.
Last edited by 2007CalSpec; 04-06-2016 at 10:53 PM.
04-12-2016, 12:24 AM
#2
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Here's some pictures of the stainless steel high flow spun metallic cats I'll be installing. They are 2.5" inside diameter so they'll slip right over my exhaust pipes. Took a bit of searching to find a dealer that would ship aftermarket cats to me and I'm so glad I found one. 
I'll be running them with my off road tune (rear O2's off). Come smog time, I'll just swap out the downpipe with HF cats for my OEM catted downpipe and reload my smog tune. Easy enough.
Measurements:
Inlet Diameter: 2.5in.
Outlet Diameter: 2.5in.
Body Length: 4.5in.
Overall Length: 10in.
Width: 4in.
I'll be running them with my off road tune (rear O2's off). Come smog time, I'll just swap out the downpipe with HF cats for my OEM catted downpipe and reload my smog tune. Easy enough. Measurements:
Inlet Diameter: 2.5in.
Outlet Diameter: 2.5in.
Body Length: 4.5in.
Overall Length: 10in.
Width: 4in.
04-12-2016, 01:46 AM
#3
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Location: Maui
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Yeah that should work fine. In the past I have run HF cats before adding the blower. Mine were ceramic. Use some tortite flared clamps and it wont leak at all. Rockauto sells them for the best price too. With a sawzall you can cut through that x pipe like butter too! LOL Make sure those cats are rated for blower cars. I know you said they were metallic but its best to be sure.
04-12-2016, 02:48 PM
#4
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Join Date: Sep 2007
Location: Nor Cali
Posts: 2,059
Yeah that should work fine. In the past I have run HF cats before adding the blower. Mine were ceramic. Use some tortite flared clamps and it wont leak at all. Rockauto sells them for the best price too. With a sawzall you can cut through that x pipe like butter too! LOL Make sure those cats are rated for blower cars. I know you said they were metallic but its best to be sure.
Features: Round STAINLESS SPUN METALLIC-CAT; 6.2L/6000lbs. EPA; 2.5in. Inlet/Outlet; 4.5in. Body; 10in. Overall; 4in. Wide; Center-Center; High Flow Exhaust Flow
I bought a sawzall a few months ago but never used it. Can't wait to try it. lol
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