you have one of if not THE nicest maxima on the .org
although im not quite on the same level, i went from a modded 97' SE to a modded wrx. I can tell you right now that you are going to miss the pimp factor of the maxima, and the refinment/luxury.
as far as power goes, i think you will be quite impressed with what the STI has to offer. and with all the work you have had to put into your max i think you will also be very impressed with how incredably easy it is to make these cars fast.
i wont go into long details here, but def. check out the sti. i think you will miss the maxima's refinment and luxery, but IMO the sti's AWD and modability will make up for that.
feel free to ask me any questions... like i said, i came from a fairly modded 97' SE and now drive a wrx. so i would be happy to help you out.