ian: i have run 25psi thru my t34 for 9000 miles now WITHOUT a dump valve and it hasnt caused me any props. I no someone who runs 37 psi without a dumpvalve and his engine has done 30000 and is still as good as day 1.

Choice is yours IMO. Chatter is better and i find throttle response is better without a d/v anyway.

Rich