I have a Cratech Box on the Black Mamba, and I have no trouble shifting beyond 6K. I usually shift around 6500, but I also have a Supercharger. Like Mustangguy said, it would be best to go to a track and test it a bit. I would expect you shift points to change from 5300 to roughly 6200+/-. Hope that helps some. Later.
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The Black Mamba 11.2@124
94 Cobra- MAC cold air fender kit, Motorsport underdrive pulley's, MAC 21/2" off-road H pipe, SVO mufflers, 3.73 gears, E-303 cam, 13.417@101.335mph