i dont know why you would drop the exhaust valve size, i thought exhaust was 2" stock in the 862 heads, help me understand this, i dont know much with this stuff so enlighten me

 

intake is 1.89" and exhaust is about 1.55" I think. LS1 and 6.0 use 2" intake and 1.6" exhaust I think.

I'm still not sold on putting stock 5.3 heads on a 6.0 with just bigger valves. GM developed the 317s for a reason. They flow more and will make more power. The only reason I can see putting on 5.3s is for cost since you can get them almost for free.

 

thanks gmctrk

 

I wouldn't mind using some ported 5.3s my self, problem is the fact that I have the lq9. Compression would be far too high. I really think a 68cc chamber would be ideal for me. Bring compression somewhere around 10.5-10.6