I have 3.08 375 hp 4 speed car would a 3.70 be better then a 3.08? 

most definatelly, it would be alot quicker, of coarse your gas milage would go down the drain and the motor would work a little more at cruise and top end world drop a little, a happy medium would be 355's which I have in the LT-1 and I get about 10-12 MPG average. anips2009-09-06 18:02:20

Just to clear up. 3:70 is the correct ratio for the fatory corvette rearend housing. 3:73 gears fit in the 10 bolt and 12 bolt chevy rearends but will not fit in the factory corvette rearend housing. I think you'll like the 3:55 better as well.