Which heads to get?
From Dons site
http://www.4secondsflat.com/FBo_EQ Cylinder heads.htm
He says" 550 + HP"
also from his site
We've spent months on the flow bench with different valve sizes and degree's of port work to determine what total combination works best, we have the formula and the parts list to get everything right.
We offer these heads in 3 stages, from a much improved stock replacement to an all out bracket package for your 318 to a 416 stroker. We've tested several cams, valve sizes and rocker ratio combo's, tell us what your trying to accomplish and we'll build you a top end package from pushrods to carburetor that will maximize your combination to the fullest. We know what works!
IMO This is an Awesome head, we're making over 600HP with our 318/375 mule and it runs consistently within a couple of hundredths of a second on any given day. They're absolutely the best cylinder head you can bolt on to your small block Mopar if you want Maximum Power, Reliability, Consistency, Durability and you want to Win Races.
You cut the light these heads will make the power.
In 2008 we'll be running a 400" combination and fully expect to be deep into the mid 10's, same heads, same ET Slayer Cam, same ET Slayer Carb.....just a little Iron Headed SB Mopar, kickin' Big Block butts all over the race track.
The Formula.....
I'll give you the basics but we're not going to publish everything we do to make these heads work:
CnC ported intake and exhaust 2 available stages
1.94/1.60 valves in a specific length
Our Special CnC mounting track for the rocker arms to allow for taller valves and springs
Open the spring pockets to allow for a larger diameter spring
Surface the heads to RA 50 for FBO Spec Cometic MLS Gaskets"
I would seriously doubt he would post 600 hp on his site if he didnt have the **** to back it up.