Building up the 400 Stroker Motor for my 1974 FireBird Street Freak, and these stock 6x Heads aren't going to cut it, even with an 8-71 Blower Cramming down the boost! It's time for a proper head-porting job on these things. It's dirty, takes forever, you'll get metal shavings places you didn't know about, but it's FREE! Check out the port-party and a bunch of updates on my Barn-Fresh Firebird project.