OK, here's what works for me. First off, lighten up as much as you can. You can take 50 lbs. off these scoots without cutting anything off the frame, just using lighter components--light floating rotor, 520 chain and sprockets, aftermarket exhaust, plastic seat pan, lighter head light, tail light and turn sigs. (I run without 'em, not required in IL), plastic chain guard, aluminum batt. box, etc.
Front end: I redrilled the nipple seats in an 18/2.15 rear rim and laced it to the front hub. Fitted cartridge emulators and straight-rate springs tuned to rider and bike weight--don't know of any good aftermarket off-the-shelf source, but Traxxion Dynamics custom wound a set for a very reasonable buck. Daytona tweak bar with a plastic fender with no internal bracing--have no issues with the set-up.
Rearsets: Tuned up the 'lectric foot, pulled the starter pedal, shaft, and gear cluster, and plugged the hole (shaved 4.5 lbs). I've seen all kinds of stuff cobbled together to retain the boot starter with rearsets, but nothing I really thought was a good option. Raask is about the cheapest rearset system, but the peg position is not only miserable, it's poor for control--above and way behind the swingarm pivot. I drilled the plate between the mounting holes to move the pegs forward and a little down, shortened and rethreaded the shifter clevis rod (the brake rod didn't have to be modded). Had to drill the shift pedal and shift collar pins out and replace 'em with bolts to alter the position of the rod so it ran straight; don't know whether the guy on the assembly line or the designer was drunk when he did his job--blame it on the long Swedish winters.
Rear: Lifted shock height to 13.25," you can go taller. Get the best shocks you can afford. I run custom Works alloy body shocks--around $550 a pair. The Progressive Series 14 is a solid performer, used quite a bit in vintage competition, for (last time I checked) just under $200 a pair with your choice of springs. An outfit called loudfastandugly.com has Red Wing hammer head shocks available for a very reasonable buck. Old Koni's can be rebuilt with Ikon components, and I've heard good things about the Ikon shocks themselves.
If your plan is to ride the bike, put function first and styling second. There's nothing like a bad seat to get your mind off cornering technique. If the roads are rough in your area and/or you run the backroads, use a sport-touring bar rather than clip-ons; you may need a bit of leverage. My machine's built as a sleeper--stock tank and sidecovers, full-length road seat (NOS aftermarket with plastic pan), mods mostly hidden; folks at LBL didn't know whether to class it as a custom or a stocker.
Lots of great rubber available for 18/2.15 front and rear. I'm running Pirelli Sport Demons in 100 front, 110 rear; good wear, great adhesion. Bridgestone BT45's get great adhesion, not much longevity.
I use tapered rollers in the steering head and needle bearings in the swingarm--standard upgrades. The scoot flicks over well, stays hooked up in bumpy corners, and is solid on the pavement right up to 5th gear redline.
Things to avoid--all 2-1 exhaust systems and any other system that hangs a pipe out where you'll grind it in a corner.
