Well, with that, the AFR castings are cheaper than LS-6 castings so......From what I was told, the LS-6's have to have the seats replaced with larger ones for the 2.05 valve to fit. Cost $125. Then you have to have new bronze guides installed. Cost $100. The AFR castings already come with these parts, so that is another $225 bucks saved over an already more expensive LS-6 head. So you get a better head for cheaper with the AFR as cast version.

 

This is a great thread on the AFR's

http://www.ls1tech.com/forums/showthread.php?t=208468

 

a set of stage IIR ls-6 MTI heads blows just about anything out of the water.