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ThreePonyStable · 06-20-2002, 09:52 AM

I have recently decided to start modifying my car a little mre and the first place I plan to start is the exhaust. I currently have stock headers and H-pipe with 4-cats. The only thing I have done is the Cat-back and I read another post that said the cat-back in stock form is the least restrictive and will give the least gains.

As for the parts I plan on 1 5/8" GT-40P headers, and a 2 1/4" H-pipe with high flow cats. Will the 2 1/4" be enough for my near stock car, I have read that the 2 1/4 is plenty for up to 300 hp and I was wondering if anyone has had experience between a 2 1/4 and a 2 1/2 pipe.

The real question is, how much faster should I expect to go. My previous best wa 13.6 and this was accomplished at sea level in 40 degree weather with 3.73 gears. Recently at 800-1000 elevation in 75 degree weather with 3.55s the car has gone 13.8. What should I expect with 3.73s in 40 degree weather at sea levl, and what should I expect with 3.55s in 75 degrees at 1000 feet above sea level?

06-20-2002, 09:52 AM	#1
ThreePonyStable Registered Member Join Date: Oct 2001 Location: Kensington, CT Posts: 47	How much faster will I go? I have recently decided to start modifying my car a little mre and the first place I plan to start is the exhaust. I currently have stock headers and H-pipe with 4-cats. The only thing I have done is the Cat-back and I read another post that said the cat-back in stock form is the least restrictive and will give the least gains. As for the parts I plan on 1 5/8" GT-40P headers, and a 2 1/4" H-pipe with high flow cats. Will the 2 1/4" be enough for my near stock car, I have read that the 2 1/4 is plenty for up to 300 hp and I was wondering if anyone has had experience between a 2 1/4 and a 2 1/2 pipe. The real question is, how much faster should I expect to go. My previous best wa 13.6 and this was accomplished at sea level in 40 degree weather with 3.73 gears. Recently at 800-1000 elevation in 75 degree weather with 3.55s the car has gone 13.8. What should I expect with 3.73s in 40 degree weather at sea levl, and what should I expect with 3.55s in 75 degrees at 1000 feet above sea level? __________________ Mine: 1991 Mustang LX, 5-speed, Mac catback, Pulleys, K&N, Aluminum D-shaft, Pro 5.0, 3.55, Lakewood shocks, SSM lift bars, Hoosier slicks. 13.67 @ 98. Sons: 1989 Mustang LX, Auto, Flowmaster catback, Mac H-pipe, Mac headers, Cobra intake, 1.7 roller rockers, 65mm Tbody, Mac cold air kit, 2400 stall converter, 3.73, 17x9 Cobra Rs, '01 Leather seats. 14.185 @ 96.8 Sold: 1966 Mustang Coupe, '88 5-speed, '69 302, Super turboes. Probably 15s. For Sale: 1987 Mustang GT, Auto, Bone Stock, with air silencer. No times.