My Lil SD was ported / G Matched. I " THOUGHT" I was having heat sink issues when I my Sat, so added a Phenolic spacer... when I sold that cat and pulled my drive train, I shelfed the spacer... big difference. Now here's the thing, according to Crap-ipeida, them 2 cars (66 Sat and 74 Duster) are almost the same #s...only other diff was the Newer headers and going electric Dist..... but Man, night and Day, Performance. Sorry for the rant/ ramble... the Strip Dom seems to work darn good, for what I have it on and in, and that is less motor than op