Exhaust runners are at 124cc's... and im going with the aftermarket for the heads because this is just a block im working with, no parts with it at all... and gmpp wants almost as much for a set of their heads as afr wants for these fully assembled ones... and as pat mentioned, the $$$ will be there when i leave so why not...yes pat that sounds exactly like the one i want to put together, if you get any #'s off the motor (as far as tq or hp) please let me know what you come up with.