well my TBSS has 4.10's stock, and at 65mph i am turning about 2200 rpm's. and both my silvy and the sub have 3.73's and they turn around 17-1800 at 65. so there's your difference. if your worried about mileage, my heavy ass sub gets 15 city every time, and the TBSS 2WD gets 14 on a good day. but let me tell you, that SS will rip out of the hole like nobody's business......but that might have something to do with the 400hp ls2 haha