Yes, I am asking for help yet again

[AMRAAM]

I am considering buying this set of 3.90 gears. http://forums.corvetteforum.com/show...ighlight=gears Does anyone in the area have the know how to swap the diff that can help me out? If need be, I can probably use a lift at the auto shop on Ft Myer. Does anyone have any experience with a 3.90 gear in an M6 car? From what I have read, it doesn't affect mileage too much and makes 6th gear more usable. Is there a downside? Oh, and if I do go this route....Does anyone need a 3.42 diff?(I think that is the stock ratio) Thanks! Leroy