Hey there,welcome to the forum.I have a 96' Ultra SP 680 stock form,the 96' has the water pump with the oil in the resoivior & site glass, witch means it needs close attention from time to time .The 97' & 98' are more maintainance free,look the same ,but no site glass,& is lubercated by the mixed fuel in the bottom end.
97' & 98' years the SPX model were avalable with factory pipes in the agressive chassis,135 hp. If you pipe the Ultra & set everything to those kind of aftermarket pipe speces ,you can release the beast from 115hp. up to 150hp.
Well ...if you really want more then look at a xcr 800 ,with the ves & reed intake combined up to 2003 models ,nice , but sometimes hard to find .