Evolution Industries 30 Tooth Sprocket and Chain Kit EV1012-1231 Raises RPM to achieve maximum performance eliminating lugging of motor Changes stock 1.352 gear ratio to 1.5333 gear ratio - 4th gear 70 MPH @ 3620 RPM to New 4th gear 70 MPH @ 4500 RPMs - 5th gear 70 MPH @ 3042 RPM to New 5th gear 70 MPH @ about 3750 RPMs - 6th gear 70 MPH @ 2570 RPM to New 6th gear 70 MPH @ about 3250 RPMs