me vs. 240 with nos

i just raced a nissan 240(the generation before the 1992 models, not the flip-up-frontlight ones). i think he has a K-motor. he told me(we were shouting out the window talking to each other after the race)that he ran 95 shot of nos, and i told him that i have the greddy kit. the whole time during the race(we went up to 60~70mph)we were around each other. at first i was half car faster than him, but than he caught up and was half car ahead of me, then i caught up again(while he was changing gear or working on the nos, i dont know much about nos). the whole time was like this. so i just wonder how many hp i might have on my car. is my car slow(have i not tune it right?)? can the turbo do much better or it is just it? (i was running 8.5 psi)i dont usually do that, man, that really hurt my engine!