Your going to get a lot of opinions on Full Systems VS Bolt ons.
Here's mine Full system gets you about 10hp maybe, plus you'll need a powercommander. Yadda Yadda. Cool if you think you need those 10 extra horses and 20 lbs weight loss.
Bolt ons take about 10 minutes and your done. Loose prolly 5-8lbs, gain maybe uh... 3hp? BUT gives your Busa a great sound and that is all I think a lot of us are after.
All that being said? I'd say go with Yoshimura hands down. Their pipes sound great, fit perfect and are top quality.
But, Bonus of the D&D pipes is that they are cheap.
So I say go for the Yoshimura B/Os. Easy, no need for additional work (usually) and you get all the sound and look you're after.