dinomite couldn't have said it any better. You definately are better off buying one brand exhaust and the price will vary greatly with whether or not you get an H (or X) pipe with catalytic converters or not. Although exhaust will make your car sound awesome, $300 dollar gears will give you alot more kick than $600+ exhaust. My opinion is the same as dinomite's.
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'84 Mustang 5.0 LX
My car