A good cheap way to go is to get GT take Off Exhaust, buy 2 mufflers from like Flowmaster or maganaflow and weld them on and throw away the stock mufflers, and to keep engine power have a muffler shop make a pipe to connect the dual pipes to your single.
I bought 2 40 series flowmasters for a good price and had a shop custom make my pipes that was expensive for me if I didn't know the people who did it.
But GT take offs is prolly the best cheap way to go.
You can still go for an H pipe dual exhaust instead of Y to dual if you are planning on doing like a super charger or something, because you'll get more power. but if you're not planning on doing any supercharger or anything, keep it Y pipe to Dual exhaust.
as for sound it's all preference. A lot of people here like Magnaflows, I on the other hand like 40 series Flowmasters. you can go to their website and hear them. or the multimedia section on
www.3.8mustang.com has people with flows and magnas.