great thread and very debatable too. Everyone has valid points. IMHO, a stock damper is more than enough for most applications. headshakes and slappers, more often than not, are a result of rider input, suspension, condition of the steering head/front end triple assembly and/or bike geometry.
The busa is heavy and "raked out" enough with a long wheelbase that it provides plenty of stability. A stock damper should provide plenty of safety, but an adjustable aftermarket one is good insurance.
I run the stock damper on my Gixx1K. 100 lbs lighter than busa, WAY LESS RAKE geometry wise, especially since I raised ride height 8 mm in the rear with the new Elka shock. It is very prone to headshakes, slappers, and front end tucks. I experience headshakes occasionally at high speeds when WFO and the front powerwheelies out of corners or straights and back down. But as soon as I relax my grip, stay on the throttle WOT, the headshakes go away and resolves themselves. The bike wants to track a certain way and it will find a way to correct itself, as long as the rider inputs don't interfere with it. Keith Code even mentions that. For me, stock is more than sufficient. I don't consider myself a slouch either when it comes to riding. I ride hard on the track--100%: go big or go home attitude. I do make some rider errors once in a while and the bike will definitely let me know. But as soon as I back off on the inputs and stay on with the power, she fixes herself real fast. Anyone who thinks all tracks are "smooth," HA!!! Try riding Reno/Fernley! That place will put Speedbumps to shame!
Reno will teach you real quick about rider inputs.
But take note, I am not For or Against an aftermarket damper, it really depends on the application and type of riding one is doing. Not to mention how much influence a rider has on their steering, and whether or not they have built a sensitivity to the overall feel of the bike.