You, or your wife, will love the change to 3.73s. Not sure how to quantify that "love" because there's no track here but believe me the gears with the tune made my wife's GTS a real fun car to drive! I'm not sure about the break in period. I read it all the time in the forum but the guy that put mine used to race Mustangs when a track existed here and said there was no break in period needed. He did recommend a fluid change at 500 miles which I did. My wife has the GTS suspension on the car with F1 supercars on the corners. I love driving her car hard into the on/off ramps here ... sorry that's all we have. I'm looking forward to leaving next year when she gets orders to go elsewhere .... I hope.
2011 Shelby Convertible w/SVT Performance & Electronics Packages
2011 Shelby GTS V6 Convertible, AT, CAI, Aluminum DS, 3.73, Tune