I had removed the midship tank on my f150 400/c6 for dual exhaust. I used some flowmaster headers from autozone about 9 years ago ($99 pair), had a local shop bend me some new pipes to dump right before rear wheel. I got some generic "turbo's". total price:

Headers $99 + tax
Mufflers (2) $40
exhaust labor and piping custom bent $135

About $280 total I think. You will definitely want the collectors welded on whatever headers you use. I had more trouble with the collectors than I cared to have, so I went back and had them welded. I am considering some new mufflers and tubbing from headers to the back. I want something stainless that wont rust which is now happening.

The best part of the whole job was sneaking to the muffler shop driving with OPEN HEADERS The sound was amazing!! I caused quite a ruckus all the way across town.