svensk
TMC's official Zombie Slayer
Jim is correct, I haven't had it on a dyno yet.
As for the heads, if I were to do it, it'd be for the bump in compression. I believe that when milled .035" with stock gaskets on an LQ4 they bring the compression from 9.4 to right around 11.0. The 243/799s flow identically to the 317s I have on there currently.
I heard if you bump the compression up that high you will need some serious octane to run it without KR? I forgot the lq4 had such low compression. My truck has "low compression" for an ls2 at 10.6 instead of stock 10.9 lol