the 4R70W is just pretty crappy stock. Go for a shift kit, Jerry Mod or get a handheld tuner to adjust line pressure and shift points. Dont forget a tranny cooler either if you start messing w/ the tranny. You might as well pick one up anyways. its only $50 and will make the tranny last longer anyways. The Jerry Mod is pretty straight forward and can be done in your garage if you're comforatble working on cars.