aw your cute....lol, 16,18,20, dosent matter, its like taking a 71 nova, puting an ls3 in it and keeping the stock 71 diff, see how far you will get. Do the math, and compare your 1st through 5th gears ratio to the final drive via various rpm sets while messuring applied pressor to clutch. Over the desired gear set, the pressor applied should be only 80% of the final drive gear times 0.376, (that would be for your gsr transaxel. Hope that helps you.