If I were to take a fully stock G35x and get an Osiris license and have it Dyno tuned how much hp increase would I be looking at?

 

You're looking at about 10~15 whp gain. Overall much more responsive and fun tho.

In your instance I would highly recommend etuning, 99% of the Uprev protuners only have 2WD dyno's so they would just be street tuning your car for the dyno tuning price... For the same tune etuning is cheaper and you get the reflash cable... much better value