I installed a full UFO 4/1 after having a Kerker 4/1, Jardine slip-ons, and of course the stock exhaust. I also have a Mark's 4/1 w/a custom can which I have never run.
To my ear, i like the Kerker 4/1 for sound, for power, but don't like the cutting of your centerstand. The UFO Dragstar 4/1 doesn't sound as good to me as the Kerker 4/1, and that is a very subjective matter. What you like may be horrible to me.
The Jardines as slip-ons are very nice in appearance, as are Supertrapp stainless steel slip-ons. Sean Morley said it, "no extra power from slip-ons," but your signature exhaust note is 'different' from stock.
Voodoo is supposed to be very similar to the UFO 4/1, is it the same? The debate carries on.
I made a canister to tone down my UFO 4/1 which doesn't appeal to the "less is more" aesthetic, as the can is long. But I was able to jet for the performance of the full exhaust, and I ended up not having to re-jet once I was done. Yes, it's large, but I can rap it on w/o alerting every LEO within a half-mile earshot of what my right wrist is doing. The trade-off of appearance for 'stealth' on sound output is worth it for me.
Look at your options, search the threads, and make your informed decision.
A start for your reading:
http://www.vmaxforum.net/showthread.php?t=31804&highlight=frankencanister