I wanted to bring this thread back up in conversation.

I also have a scarab III with 330's and TRS drives. I am running 23P Mirage Plus'. RPM are 4600, top speed 48mph on GPS. This seems really slow to me. From what I've read I should be running high 50's easy. I wouldn't mind pushing up to 5000 rpm as long as the top speed is significant enough. Ken at Prop Gods suggested 22p bravo ones if I can get a set to fit the TRS drives.

Any thoughts on this?

Something doesnt sound right. You should be running a little faster. Make sure the hull bottom is clean, no scum, and try some 4 blades..21-22p. TRS props and bravo one props are the same. Well, propshafts are same. Also, my buddy is now turning his hydromotive 22's inwards (switched drives left to right) and he says he picked up some speed from that.

48 mph at 4600 rpm is not bad with twin 330's in everyday trim ( stuff, fuel, folks ) and 4600 rpm is at the top end of the torque curve. double the hp and you can run in the low 80's with a 29 or 30 pitch prop.
maybe.

This sounds about right as my friend has around 620hp and now runs mid to high 70s with Konrad shorties fully loaded.