ported j heads

i have never tighten the lash up that tight cam calls for .018 and .020 i did tighten both up .002 and didnt see any differance. theese heads flow 258 @ .550 on the intake 180 on the exhaust by memory. i also get to do lots of valve jobs. next time i will stay with 2.02 on the intake also. as far as seat pressure i was just trying to squeze a little more horsepower thats what seatpsi i found for the 400lbs open.