Convex -- From what I've been learning, yes... drum-drum setups truly don't need a prop valve, same as disc-disc... no need. I wish this were in writing from vendors.

Mopar Mitch "Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers! Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!