Trying to Choose Rev/CDI box...

Not trying to be a nay-sayer but, you can buy two identical new cars, trucks, quads or whatever and one will out perform the other.

You list a Dynojet kit. Who installed the kit and calibrated it? Installing a jet kit will not necessarily give you more power (especially on the top end). If you installed a larger main jet, you might want to jet down 2 sizes and see if that improves the 5th gear power. Likewise, manufacturing differences in the carbs and engine might be affecting the power.

If you just got to beat your buddy, take into account riders weight (better yet, weigh each machine with the rider wearing all the gear he normally wears when riding), tire pressure (higher pressure = less drag, but too high of pressure can result in loss of traction at high speed)(if your tires are slipping and your buddy's tires are not, you could have more power and he will still pull away from you), riding stance, etc. Now if you can ride his machine while he is riding yours and his machine still pulls yours, then you need to make a minor change for that 5th gear power. Maybe you could get both machines dyno tested.

A Power Now device in the carb might help by reducing "power robbing" turbulance in the venturi of the carb. Having the cam degree'ed can help. Advancing the ignition with an offset flywheel key might help. Just changing to a lighter viscosity oil might do the trick.

Good luck and let us know what you discover.