is actually cheaper than the price listed on the Magnaflow site. You can get it for around $500. The TPR exhaust is $450. Both should make more power than the Magnaflow due to the larger piping.
The Kazuma is 2.5" all the way back, and EXTREMELY loud (not street legal by a long shot). All three above are street legal, and moderately loud.
What's a resonator? So you have a custom catback? How much was it?
The resonator comes after the cat and before the axle back. It's basically a long muffler tuned to get rid of high frequency raspiness. As for a custom cat back, the one thing you NEED to remember is to have the piping mandrel bent. Crush bending will just restrict power, and basically waste money.