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Old 07-08-2003, 02:08 AM   #1
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Default Porting Exhaust Manifolds.

Will polishing/freeing the flow on your exhaust manifolds cause a decrease in torque? I already increased my exhaust to 2 1/2", with a free flow cat, and dual free flow mufflers. I have noticed some decrease in torque, and am concerned that the polished manifolds will only increase the problem. Also what can I do to increase my torque again aside from constricting my exhaust again?
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Old 07-08-2003, 03:11 AM   #2
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You may lose more, but it probably won't be noticeable. To gain some torque back, port and polish your TB and lower intake/heads. Let the front end breathe better, too. I'm surprised you lost torque with a 2.5" exhaust. I wouldn't have expected that. Was it 2.25" Stock?

I'm thinking it must be the dual mufflers killing you. Give us more details on your setup....where the Y is, diameters before/after the cat and mufflers, etc. Even the type of cat and muffler.
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Old 07-08-2003, 10:56 PM   #3
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Most of that info is in my sig. The cat and the resonator are 3". The mufflers are just behind the bumper. There is about 24 inches of pipe from the mufflers to the Y. All the pipe between the mufflers and the cat is 2 1/2 ''. Porting and polishing the TB sounds like a fun idea. How is this done. Can I do it? Do I need to send it off somewhere? Should I buy one that is already done (or perhaps larger throat) and install it? How much does this cost?
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