Much has already been said so I won't repeat things like extended swing arms, wheel stripes, etc.
So thinking about other things specific to SP's... Don't get me wrong, I'm not being critical of anybody else's bike, just commenting on what I wouldn't do on my own bike. These are my thoughts:
I'm not a big fan of LED marker conversions to SP headlights, nor projector type headlights. They alter the looks of the bike in the wrong way, IMHO.
One sided exhausts. They look fine on one side, but take away from the proportions of the bike when looking from behind. The SP's always looked better with two in my eyes. The only possible exception being two silencers on one side.
Polished wheel rim edges. These to me give the impression the wheel got scratched up in a fall and someone's tried to hide it by polishing. I did the same on my enduro bike a long time ago...!
Ditto with wrapping headers. Just adds the suspicion that someone's hiding link pipe rash.
Scott steering dampers. I know people like their function, which is fine - Me, I just don't like how busy they make that part of the bike look. Would rather see an Ohlins, Matris, etc. on mine - if I were fitting one (Which I'm still sure I don't want).
Too many instrumentation add on's. Gear selection display, ditital temp diplay, sat nav, radar detector, etc. Again, takes away from the simplicity of the original "race style" display.
Crash Bungs. Because the fairings have to be drilled to fit using most SP kits.
Bar end mirrors. Prefer them in the original location, myself. Can't imagine bar end mirrors would be very effective, although I've never used them.
Bestem / Clever Wolf tank pads. They're probably effective, but just don't go with the original graphic designs. It's a good thing Duck is making more aesthetic alternatives now.
I'm sure there's more - but those are the main ones I wouldn't want on my SP.
Euro RC51 SP2: HRC WSB Ti Hi-Level, T1 Airbox & Snorkel, PCIII, Dymag CA5 Carbon Wheels, Ti64 Spindles (F, R & Swing Arm), Mori Link, Maxton GP7 Shock & Ohlins 832 Forks, Brembo GP Calipers & SBK narrow track (F), Braketech Disc (R), Brembo billet Underslung x 2 Brembo RCS, Tyga Triple, 7075 Stem, Probolt Titanium all over, Babyface rearsets, MR Complete Carbon Lineup, Custom Undertail & CBR 1000 LED, Watsen LED Indicators, Harris Brace, Giles clip-ons, Corbin seat, etc. 2013 BOTY.