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.

i already have the HP exaust manifolds. I was curious did an aluminum intake give me more HP then the stock cast iron

If your concerned about low pressure that being 40 down the highway just shim the oil pump valve possibly 0.60 with a washer and see the improvement. 1000 rpm per 10 pounds of pressure.

logan426

How do I shim the valve? Can this be done without taking off oil pan etc.? How involved is this?