Pretty much all aftermarket exhaust is going to be somewhat loud at highway speeds (some have Db killers available). All of them will give you about the same minimal gains in HP.
In the end it comes down to your budget and what you think looks best.
I have the Scorpion Carbon Fiber pipes. With the new look tips they now compete in the looks dept. with the more expensive competition.
My choice came down the the Two Bros. in Stainless (carbon option was way more than I wanted to spend) or the Scorps in Carbon...the price difference made it an easy choice (had they still been sporting the old style tips...well...who knows). Also, judging sound from you tube clips and other soundfiles can be tricky. All are compressed and very few, if any, were recorded with pro sound capturing equipment. Keep that in mind when making your decision.
Here are mine, freshly installed:
BTW, if you are interested in drilling out the exhaust but afraid of not liking the results I have my stock can laying around. Spring for shipping and you have a throw away test system!