Sounds reasonable...might be able to get it cheaper, I honestly don't know I do exhausts myself as I have a welder....I've never had one done. So they will do a y pipe from where the stock muffler was, then run the duals? You may want to swap your stock y pipe where the manifold down pipes come together too, they might throw it in fairly inexpensive since you are giving them work, and it helps performance a lot. magnaflow makes a good y pipe you could swap to, it's about $30 for the part.
Breathing in and out is good enough for me.