Depends on what your budget is. I have the GT40-Y303s. Couldn't pass up the deal of new, never been fired aluminum heads for only $724 to my door. I bolted them on and instantly went 0.4sec faster in the 1/4mile. Sure, I would love a set of AFRs. They are some of the best set of heads out there for the money. But, even used they cost more than I spent. The Y303s can be ported/cleaned up to outflow the GT40-X303/5 heads.