If you increase compression you increase HP but you also increase the chance for detonation so you either have to run higher octane gas or retard the timing or put in colder plugs or all the above.

 

okay well i have this question then, where can i get a thinner head gasket, and/ or what brand makes them.

 

dude forget compression. seriously. that's 60's type of thinking for power. if you mill the heads .030" all your going to get is 7hp tops.

port the heads and the same gain is there and the ability to make more power with additional mods.

the 3.8 is already a high compression engine stock at 9.4:1 what more do you want 10.0:1??? it won't add any power for .6 of a point.

forget about compression if you are running stock pistons. the best way to increase compression is to run higher compression pistons. milling the heads to make more compression is stupid. all it does is thin the deck of the heads out to the point where they won't hold a headgasket without blowing.

do yourself a favor and port you heads ( send them to me and i'll port them cheap) get a cam and a nice poweradder

 

YOU COULD UP GRADE TO SPLIT PoRT HEAD AND MANIFOLD

you can go to a scrap yard and find a F150 with a v6 get the heads and upper and lower intake manifold

you will have the same heads as a 99-04 and a better manifold with taller runners then what the 99-04's had the only problem you may run into is that the taller runners may not clear the hood but im not sure