i have p/p 5.3 heads and r shaved .030 and my compression is around 11.3 to 11.5 my don't flow as good as yours.you will need to unshround the valves witch is easy and make a difference.don't worry about piston to valve clearence i have .100 plus so don't worry.

 

what size cam you running devil?

 

I also have bigger valves in my 5.3 heads Ive got some pics on here of the unshrouding I had done.

 

Got a link to the unshrouding post? I found a few where you mentioned you did it but none with how or pictures of it done.

I'm going to clean the heads up and take a few pictures tomorrow.

 

Found an old cutout vid http://video.ls1tech.com/Player.aspx...4-CBFB37824E46
but no pics I think they got lost when the site switch over was made, thats too bad because they were good pics and I dont have em on the comp anymore

 

sweet vid

 

running 216/220 with soild lifters and 1.85 rockers gives me around 579 lift on the high side