I went the 3.73 route when I had mine, it greatly improved drivability. The stock gears weren't great for normal driving, felt like I needed to slip the clutch to get it going from a stop light.
When i 1st got my 2008 Gt500 the 1st things i did was the 3.73 drag pack and frpp handling kit. Hated the stock 3.31. Car was Night and day.