What speed would it run with 525's and or 600's?

With 600's you should see the low 90's. Magicfloat had a 353 with 600's and I believe he got 94 GPS. 525's, not exactly sure, but I would guess low to mid 80's.

When powerboat magazine did one with 600's it went 91 I think it had boxes too.

93,3 MPH
600 ITS + shorties

And a pair of five blades Pokerruns probably could do a little better with 4's
My 353 with 500's best GPS numbers were 82 and change with labbed 29 hydros 80 with the 27 five blades non labbed. So a 525 package should be somewhere in the middle.
Nice GPS showing port and starboard RPMs what kind is it?

If you post this on Speedwake he'll see it and chime with an answer for you. Of course that fast Alabama water is hard to match anywhere else in the country.

[QUOTE=Nice GPS showing port and starboard RPMs what kind is it?[/QUOTE]

Not a GPS for navigation. Mercury SmartCraft SC5000 system view! I have the same thing and love it.