I think your best bet is to check out some internet videos of people with similar cars and different exhausts and see what you like the look and sound of. That's what I did when I was searching for an exhaust for my car. When I found the one I wanted, I just searched around online and found the cheapest place I possibly could and bought it from there. It's really a decision you have to make by yourself.
And as far as installing it, it's extremely easy to do if you have a floor jack, jack stands, a set of simple hand tools (you'll probably only need a wrench), and some lube if the rubber exhaust hangers are stubborn for whatever reason. Be sure to replace any gaskets too.
07 WRX (Albins 5MT + Blouch 20G)
Jorge Carrillo Tuned (365 whp/340 wtq)