after searching spyderchat this is are comparison between the 6 and 5 speed ratios Manual -- Standard 6 speed 5 speed Manual Gear Ratios 1st 3.166 3.166 2nd 1.904 2.050 3rd 1.392 1.481 4th 1.031 1.166 5th 0.815 0.916 6th N/A 0.725 also foundUsing chrisngrod's numbers, if you were to shift at 8400 RPM, then the RPMs on the next gear would be as follows: 5 speed: 1st to 2nd: 5,052 2nd to 3rd: 6,141 3rd to 4th: 6,222 4th to 5th: 6,640 6 speed: 1st to 2nd: 5,439 2nd to 3rd: 6,068 3rd to 4th: 6,613 4th to 5th: 6,599 5th to 6th: 6,648 So, as you can see, with both gearboxes you'd miss the hot cam when you shift to 2nd gear. The theoretical top speed is 157 MPH for the 5-speed and 168 MPH for the 6-speed. If you wanna cruise at 70 MPH, you'll be at 3,735 RPM on the 5-speed and at 3,490 RPM on the 6-speed. If you are running a 1/4 mile race, you might only have to shift 3 times with the 5-speed (124 MPH max in 4th gear), and 4 times with the 6-speed (105 MPH in 4th gear). this Reverse 3.250 3.250 Manual Differential Ratio 4.312 4.529 so with these figures what can you make out of them?