3 1/2in cat-back
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Joined: Mar 2002
Posts: 2,516
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From: San Antonio TX
Car: 1990 G92 IROC Z Miniram
Engine: 388cu 6.4 Liters
Transmission: G-Force T5
Axle/Gears: 3.73 Gears
3 1/2in cat-back
How much HP do you think I can gain with a 3 1/2in cat-back? Look at my sig!
Joined: Sep 2003
Posts: 25,895
Likes: 429
From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 3 1/2in cat-back
10-15 whp my guess. Try disconnecting current catback at the y to see if it helps.
Thread Starter
Supreme Member
iTrader: (2)
Joined: Mar 2002
Posts: 2,516
Likes: 5
From: San Antonio TX
Car: 1990 G92 IROC Z Miniram
Engine: 388cu 6.4 Liters
Transmission: G-Force T5
Axle/Gears: 3.73 Gears
Joined: Sep 2003
Posts: 25,895
Likes: 429
From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 3 1/2in cat-back
You are makin great numbers for that setup. It def should pick up if muffler flow doesnt restrict it. I have seen 7-15 whp gains with cutouts on similar power setups, bypassing the 3" catbacks
Thread Starter
Supreme Member
iTrader: (2)
Joined: Mar 2002
Posts: 2,516
Likes: 5
From: San Antonio TX
Car: 1990 G92 IROC Z Miniram
Engine: 388cu 6.4 Liters
Transmission: G-Force T5
Axle/Gears: 3.73 Gears
Re: 3 1/2in cat-back
This is about the only thing thats left for me to do to create more power out of this combo. The rest of it is getting the power to the ground and my driving. It should be able to run in the mid 11's@120+mph as it stands.
Joined: Sep 2003
Posts: 25,895
Likes: 429
From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: 3 1/2in cat-back
Yup my 383 made 392 whp heat soaked on last pull. Ran 119 mph that night in ok air conditions at 3450 lbs
Senior Member
Joined: Jun 2001
Posts: 922
Likes: 33
From: Kansas
Car: 91 Z28
Engine: 6.0L LQ9
Transmission: T56
Axle/Gears: Dana 44 3.92
Re: 3 1/2in cat-back
you're not losing anything with a hooker max flow muffler, it flows as much as the 3" pipe. the 3" might be the only thing holding you back, other than the cats.
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Thread Starter
Supreme Member
iTrader: (2)
Joined: Mar 2002
Posts: 2,516
Likes: 5
From: San Antonio TX
Car: 1990 G92 IROC Z Miniram
Engine: 388cu 6.4 Liters
Transmission: G-Force T5
Axle/Gears: 3.73 Gears
Re: 3 1/2in cat-back
Well since I'm in Cali I need the cats. Beside I don't like the raw exhaust smell. It stays on your clothes. 3 1/2 I think is the way to go
Senior Member
Joined: Jun 2001
Posts: 922
Likes: 33
From: Kansas
Car: 91 Z28
Engine: 6.0L LQ9
Transmission: T56
Axle/Gears: Dana 44 3.92
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