When i run n/a it kinda revs high then shifts, it doesn't bang the limiter but really close. when i ran a 100 shot of n20 it banged the rev limiter then i let off and finally shifted and got back in it other than that feels strong. i have not tuned it and and its completely stock, is it going south or is there something thats cause it any help is good.

Mods are in sig

 

Well you are adding power with the stuff your doing but failing to realize that the time required from the PCM command to shaft and the actual shift is constant. So when your driving for instance without the shot the shift occurs close to the rev limiter but when you hit the spray the RPM rise faster and there is no longer time for the shift to occur before the rev limiter.
Tuning may help and should be done however if the trans is really also at 134k its likely getting tired too.

 

good to know about shift time. even though the trans is at 135k it feels great better than my 02 chevy 4l60

i guess i will play around with the trans tune.

 

You are going to have to tune it for the NOS. In most cases this will correct your problem if the trans is still in decent shape. Vince