Yamaha's YZF750SP was made from 93-97.
The first 2 years (93-94) the difference between the "R" was:
-FRP 1 piece solo seat
-Keihin FCR39mm Flat-slide carbs
-Air Scoop on top of radiator
-Endurance windscreen (lower frontal area)
-Needle thrust bearings
-TPS sensors in throttle and gear
-Fully ADJ front suspension (93 "R" forks = preload only)
-Fully ADJ Rear Shock w/stiffer spring (very harsh ride compared to R's softer shock)
-Close-Ratio racing transmission
-Different suspension linkage
-Michelin TX11/23 Hi Sport tyres (vs Bridgestone BT50's on R model)
From 95-97, Yamaha also added to the SP:
-Ohlins shock w/remote preload adjuster
-Adj swingarm pivot
-Bolt on sub-frame (more forward position)
-Slightly revised fairing panels
YEC KIT Parts are EXTREMELY DIFFICULT to find now and most of the parts are discontinued. However, with LOTS of PATIENCE, it is possible to find some brand new parts and some used parts. Your search will be WORLD WIDE as I've sourced parts both from here in North America, Europe and directly from Japan.
YZF750SP's respond very well to a HIGH QUALITY, FULL RACE exhaust (jetted properly of course) and you can expect an immediate 10HP gain (at rear wheel). This is the first thing you want. Keep in mind, you'll lose the bottom end and midrange since you'll be dumping the EXUP but it's a track bike anyways.
Send me your e-mail and I'll give you a copy of my '94 YEC KIT manual in PDF format........lots of COOL stuff in it!!