I tend to agree with the advice given here. I second the gel seat..the stocker really bothered me after only about 100 miles. Suzook gel (from StreetnTrack) I go 300-350 before feeling it. Zero gravity double bubble windscreen for better airflow/proection (I'm 5'8"). Stainless brake lines for better feel and performance, TRE for less lurch at low speeds in traffic.
Tank bag (with straps) and I use a soft luggage on the rear seat when touring, pillion when not. Gel grips. Relocate Input air temp sensor
(IATS) if you plan to ride in traffic in hot conditions...Muzzy aluminum fan blade too if in hot conditions/traffic.
One item not mentioned above...Scottoiler automatic chain lubing system
About $170 and I got the larger touring reservoir (about the size of a paperback book) capacity good for 3000-4000 miles. The reservoir lives under the license plate, drip rate to chain is hand valve adjustable/variable to easily compensate for dusty or wet or high heat/velocity conditions. Extends chain life (they claim 2-3 times the mileage) and reduces adjustment interval...no need to pack sticky chain lube cans on a tour or worry about when/how much to apply....Busa was my first bike with NO centerstand so applying chain lube away from home/pit stand is a pain.(SIDESTAND MOD!!!) It is really just a bunch of thin teflon tubing and a small reservoir/valve that really reduces wear, drag, and worry.
The install is pretty easy, requires "t" connect in to a vaccum line so oiling only happens when engine runs!!! The lube applied is pretty much the pink ATF fluid so it doesn't generate the sticky residue that attracts dust/grit like conventional chain lube. I have 7500 miles on my 01 Busa with 3 chain adjusts to date...no appreciable wear on sprockets either!!!
Weighs maybe 1 pound or so and is not really visible/obtrusive...This is my favorite Busa mod by far. I think it is made in Scotland (those frugal souls) and I got it through Riderstation.com?? in Chico,CA.
Other considerations: depending on your weight/load probably a set of 1kg fork springs, and I also got an Ohlins rear shock (not for comfort though).
Scorpio alarm system with perimeter sensor, pager, panic feature etc for some peace of mind when away from home.
While several of my suggestions are for the Busa's comfort/performance, in the long run they reduce wear and tear on the rider...e.g. no overheat, melted fan blades, jerky low speed performance,"follow the bike around the lot chain lubing" etc to deal with...
I agree with those (including Suzuki) who call it the best "open class GT machine" out there.
I remember returning from a "Northern Cal loop" tour south of Lassen Volcanic Park and just rolling on the throttle up to 165mph or so....smooth, solid, stable..some tourer huh???
Tony