Exhaust?

[Z28]

Well to be honest, my exhaust is raspy, noisy, and rattles like no other car i've ever been in. In order to fix this, I need to get new y-pipe and a cat back.

Back when I first got my car, I ordered a TSP Rumbler and well it didn't exactly fit too well. At this point I can't return it and I don't know if I should sell it or have an exhaust shop add on to it (muffler, extra pipes, etc)

Soo basically its this:

What y-pipe would you guys reccomend?
What shop would you reccomend getting it done at?
Should I sell exhaust and get a new one?

Thanks in advance