Can anyone form SC tell me what the specific difference between the Raptor 400 VS 450 is ?

Is it cams and Tuning? What would it take to turn a 400 into a 450?

I am trying to justify the $7600 price tag for the same exact mill.

404 LB-FT OF TORQUE
350 HORSEPOWER
89 OCTANE UNLEADED (MAXIMUM 10% ETHANOL)


452 LB-FT OF TORQUE
410 HORSEPOWER
93 OCTANE UNLEADED (MAXIMUM 10% ETHANOL)

Furthermore, what is the BEST Surf Prop for each engine with the W/1.76 Transmission?