with my setup (86 saltare with 454 and ~2000lbs ballast) a modern prop (Acme 209 13x12.5 4 blade) turns a few more RPM at loaded surf speeds (for me around 2400 RPM @11.2MPH) but holds speed WAY better, gets to speed easier, and respoinds to small throttle changes (made by GPS Ridesteady) more quickly than my stock prop (13x13 1986 vintage). It seems to use less fuel although it's turning a couple hundred more RPMs at the same speed. I feel like it has some affect on my wave, but maybe it's just superstition... I whacked my Acme on a log a few weeks ago, and it was out for repair over Memorial day so I was using my stock prop as a backup. I got it back for this past weekend, and I truly noticed a difference in both performance and "cleanliness" of my surf wave in back to back weekends.
Korey Morris -
Sold to Arkansas: 1986 Supra Saltare
Current: 2018 Moomba Craz