Depends what you're after. For flow, yes a straight through design like a Magnaflow is the best choice. But when it comes to sound it's whatever sounds good to you personally. Everyone has different taste. I'd suggest listening to some good YouTube clips of the different mufflers with good headphones. It will at least give you some idea.
By the way, I saw you posted this in another section as well. Not supposed to post the same thing multiple times. It's a against the rules and frankly really annoying. Just a heads up.
I'm not sure, haven't been to their site in a while and I'm on my phone at the moment otherwise I'd take a look for you.
Again, YouTube is probably your best bet. There's literally hundreds of videos if not thousands of people doing start ups and ride alongs with their exhaust set up. Just make sure you have good headphones to listen. Speakers won't do it justice.