pcm reprogramming

[Gmtech1005]

I have put a 3.73 ring and pinion, and limited slip carrier assembly out of a 2001 t\a into my 1997 firebird. It is replacing the stock carrier with 3.08 gear. I wired in a speedo box to correct the speedometer situation and put a thicker tone ring in to combat the rear wheel speed sensor not reading problem. The car is almost fine, however the shift points are off and I am thinking a pcm reflash is in order. I am planning on major mods this winter while she's in storage, so pcm reprogram info or chip info would be much helpful. The 3.73 really rips in that car, just shifting from park to drive the other day with my b&m electronic shift kit in performance mode, it broke em free for a split second. It was only a chirp, but i had my foot on the brake and giving it no gas. I thought it was cool atleast. Either way i need reflash info