Engine speed and pulley size alone doesn’t really matter. What matters is the relationship between the two as this will determine how fast the supercharger spins at any given RPM. I’m not sure why you would want to run up to 8500 RPM anyways. DI platforms become increasingly limited at higher RPMs as the window to inject fuel becomes increasingly smaller. I would chose a lower RPM, smaller pulley, and more torque across the power band.
Because he is a skreet racing fool who thinks if your motor can spin 10k RPMs it will be faster than anything on the skreets. He must have came from the VTEC civic world IMHO. He can’t grasp the concept of a power band and how important it is to stay in said power band…regardless of where your redline is.