You are not off topic at all. I dont think a mani swap will give you what you want. You want to attack the most restricted area of the air pump (eng) which is most likely the exhaust. logs to HP manifolds and a MANDREL bent 2&1/2 or even 3" pipes w "hemi" Dynomax super turbo muffs w an X pipe and resonator muffs of some type in the rear tailpipes for noise reduction (required w 3" system). Or headers (& the above) for more gain but with their attending headaches. Any ex dia restriction (collector reducers/compression rather than mandrel bends restricts flow out & hurts performance.