I'm starting to piece together my ls/build and am having piston quistions I know the jdm p30 pistons will fit my ls rods with out modification but has any body had any sucsess with the ITR'S OR THE CTR'S on the ls rods do i have to mill the rods 1 mill on each side of the small end of the rod? And i will change the rod bolts as well my head will have a port/polish is it a good idea to do a valve job should i use flat valves will i have piston to head clearence problems I'M just trying to get the most out of my head as possible for better flow any help will be great looking for 190/195 hp

The machine shop will take care of what needs taken care of when mating your pistons/rods. So don't worry about that. Just explain to them if they're not familiar they will need to machine the rod to fit in the pistons.

If you're sinking money into the head with a reputable cylinder head shop then the 3 angle should be included in your port/machine work etc.

What head are you using? LS? Does anyone make flat faced valves for that head? The flat faced valve will not be more prone to piston/valve clearance than if you used a stock valve. so, when you build this engine, do it right. Clay it for proper piston to valve clearances and degree the cams.