I have a T56 in my 01 Formula. I'm putting down 400 rwhp. I want to start doing some autocrossing and track days. I'm thinking about going to a 4:10 in the rear end over the stock 3:42 to keep the rpm's up. The cam .591 lift on both the intake and exhaust and a 110 LSA. opinions?

 

4.10s' are the most common/popular gear change mod for M6s'. Since we're discussing the stock OEM 7.625 10 bolt,the 3.42s' are the strongest and as in any form of racing,M6s' and sticky tires wreak havoc in the rear.

 

It comes down to the redline on the engine, the max speed you expect on the track, the tire diameter you are going to run, while avoiding the use of an O/D gear.