Gm is selling the LS9 as a crate engine.. Pop that into the V6 and it would be the ultimate performance mod
Just kidding.. As far as I know the hurst short throw shifter is a good performance mod as it was used in the 4.6 0-60 time as well as the high wing spoiler as it works better in the wind-tunnel tests. I don't know about buying and installing the catback, intake and headers on the V6. I think you should save up for the V8 in your case from the sound of what you want to do to the V6..