if you have an 07 classic truck(looking at your sig picture you do) you have 862/706 heads
the nnbs 07 trucks came with the 799/243 heads

 

Yea I didint wanna buy the same head I already have lol

 

To expand on this. Larger runners, and a larger intake valve. It also has a larger combustion chamber, thus the need to mill them.

 

excellent thread so far. love to see some before and after numbers to come full circle with the ideas.

 

I'm curious as to what happens if I put the heads on without that .030 mill?

 

loose compression and lowend torque...be lazy in lower rpms

 

hmm I see what about that HP gain is it still good without a mill

 

will lose velocity and yield no gains because of the loss in compression, it's more noticeable down low but if you take the .030 cut heads vs non cut heads, the .030 heads will still make more power than the un-milled heads. they'll be missing that "quench"

 

Turns out mine aren't milled...having em put on today so will see if they were worth it lol

 

you could also throw in thinner gaskets to help as well. also check push rod length to be sure your good.