Heck do what I did, No real performance gain, maybe 6-8 lbs of weight lost, but still makes the bike feel and SOUND sOOOO much better with very little hassle. So, if your happy with the way your bike performs, find some good used bolts on's off the board or on ebay. Maybe head over to Yoshimura or D&D if you like it loud. Spend about $600 for a pair of Stainless Bolt ons and enjoy the sounds. Then later on, assuming you decide to go to a full system, you sell the pipes you have for about 2/3rds what you paid, add a few hundred Bucks and you have your full system.
It really comes down to what YOU are looking for. Hungry for more performance and power? Have to get a full system, no way around it. Want to give your bike a nice sound without any hassle, AND NO REAL PERFORMANCE GAIN? Get some Bolt on's and don't look back.
My biggest point would be that Bolt ons are super easy, literally 15-20 minute job and your done. Full system requires some real work, extra parts, and some tuning but you will get real power gains... like 10-15 horses I believe prolly more with BDE...
So its what you want... Oh and looks? I like the Dual exhaust look a whole lot, so for now Bolt ons were the easy, hassle free answer for me, But HMF makes a dual exhaust High mount full system that is the cats ass!!!