If you are trying to make a street legal XBRR that is street tuned then I would recommend you do the following things....
1. Revolution Performance Engine Performance Kit
http://www.revperf.com/XB9-XB12/xbPerformKits.html
1474cc XB12 Monster Bore etc.....
2. Equal length headers
http://www.trojan-horse.co.uk/prods/84.html
better picture here...
http://www.trojan-horse.co.uk/prods/78.html
3. Street tune your ECM with this GSD map and ECMSpy or you can run the Buell Race ECM (be sure you run the open airbox conversion and catch can with this engine setup to keep from choking the engine)
http://grandstanddesigns.com/shop/index.php?l=product_detail&p=49
4. Firebolt front end and Lightning Tail section with Buell CG seat and Radiantz LED integrated tail light and turn signal combo (see pg 5 of this forum)
I would also recommend (provided money is no issue)
-Buell Race Series front rotor with ZTL2 conversion kit if you have the 6 drum caliper... Also do the Nissin Front Master cylinder with 19mm radial reservoir
-The Brembo rear brake mod (with new brembo master cylinder)
-Passenger pegs for the rider position (instead of the 1" drop pegs) to increase lean angle
-Buell Race Suspension
-Barnett clutch kit (or the Buell Slipper Clutch)
-Muller Power Clutch
-Magnesium Wheels
-Carbon Fiber Body work
check out this chin spoiler belly pan combo!
http://www.trojan-horse.co.uk/prods/33.html
-And a custom rear pulley like this one... just for a cleaner look
http://www.trojan-horse.co.uk/prods/171.html
This combo will run you over $10,000 but will give you the absolute optimal street version of the XBRR... adding the rev perf kit to your motor will give you over 120hp and 100 ftlbs!!!! Which is the perfect amount for the street... any more and you would be robbing yourself of acceleration
because you would have zero traction