Questions about I/o to outboard conversion

[RidgeRunner]

I ran a 21P Thunderbolt (Mirage Copy) and a 23P Tempest with vent holes for holeshot (signature picture) When I switched from your 250 EFI to the 250 XS I lost about 3 MPH. I took a old Tempest 25P and had it customized to get my MPH back. They knocked some of the pitch out and cleaned up the edges. I think I would try what you have first. It had ought to be close. When in doubt, trim it out...