I was measuring up gears on a spreadsheet I made as well. With the TKO I'd be coming out of 1st at 35.7 MPH@6500 RPM's, which is pretty tight and probably perfect for Autocross. However, at 65 mph in OD (.68) I'd be running 2463 RPM's. Not terrible but in my Charger now I'm pushing a 4000 lb car at 65 MPH around 2000 RPM's. I'll probably be driving it on the highway far more often than racing it but I was thinking I may shoot for something more in the range of a 3.91 instead. Have you any concerns of the 4.56's heating up while driving normally?
