I have a 99' Baja 302 w/310's. Currently running 23 mirage + props. It runs great, about 63 on gps, lots of power, right on the rev limiter with lots of trim. Anyone running 25's or any ideas for more speed without alot of power loss

Might be worth trying a pair of Revolutions, they pull about 300 RPM less than a Mirage in the same pitch. Depends on the boat, but they can be worth a few MPH, much better cruise. See Revolution

Is that a mercury brand prop, I"ve never heard of them?

Yep, it is a Mercury prop. Problem is it is only available up to 23". Power Boat did a test a while back and it was faster (or as fast) as a Labbed Bravo. Every boat is differant, but when it works it works great.