I have an 02 gt and I just got my car on the dyno the other day and I made 260rwhp n/a and when tuned for nitrous I made 240 rwhp n/a (guessing cause of the 2 degrees taken out) and then made 315rwhp on a 100 shot from nitrous express basic wet kit. I only made 75 rwhp on a 100 shot. Bottle pressure was 900-950 and nx claims 1050 for optimum power. Could this be the reason why cause my bottle pressure was a little low?

 

Your pretty much answered your own question. Raising your bottle pressure would probably get you another 15 hp. More power can come from thye tune...all depends on how far you want to push the tune.