Here is a little tool I made to help you guys out who are always wondering what your engine speeds are going to look like if you change gear ratios.  I have started out with just the stock 4th gen F-body stuff, but will be adding more options later on depending on requests.  Leave a comment for any requests!

(Axle Ratio x Vehicle Speed x Transmission Ratio x 336.13) / Tire Diameter

(First Number x Second Number / 2540 x 2) + Third Number