Speedmaster aluminum heads

I got 2 sets in use...one set was hand ported by IMM with 2.05 intake valve on a 71 Dart 360...Ran has run a best of 10.50s in Las Vegas.
Second set is on a 75 Duster 360, it was a bare speedmaster cnc version that a competition valve job was done on...it has run a best of 11.19 in Vegas, this engine does not have the same quality parts as the other 360 does....

So yes they perform if they are done right...