I had my 4l60e completely built. anything from hardened shafts, beast sunshell. perfomance clutches..before i had the car tuned at vector it shifted fine. but after the tune it short shifts when i go from a dead dig in drive. but then if i try to shift it manually most of the time it will bounce...
i have a set of 5.3l heads and i hear they work really well on an ls1 because they up the compression ratio. and flow better than ls1 heads when ported but they do have a smaller intake valve than the stock ls1 heads. is it worth it to have them ported and polished and have bigger valves put in...