I bought my N1 dual from enjuku (banner at the top of the page). Cat back exhaust cost me a little over $500 delivered if I remember right.

You shouldn't need a shop to install it. It hangs from the stock hangers and bolts to the stock cat.

I was going to have a similar exhaust custom made at a shop, and by the time I bought the mufflers and resonators an had them custom fabricate the piping it was going to cost just as much.

-Justin