headers vs manifolds on a 318 2bbl difference ????

ir3333 said
below 3000 is where everybody drives 99 % of time.

Not at full throttle

ir3333 said
1200 rpm to 5200 rpm is plenty on the street
and usually provides better lo rpm torque instead of high rpm hp.

You only needs 40 or less hp to maintain speeds which is a 160 tq @ 1313 rpm and 80 tq @ 2626 rpm. The drivability is how well your car part throttles through the speeds.