Your 4.6L comes with a stock 80mm MAF, which is a great size. However, there is a post in the middle which takes up a lot of space. If you go to mustangworld.com, there are instructions to remove to post with a hacksaw and a dremel tool in their "How-to" section. Thats what I did, and it worked great.
As far as the TB, 70mm is a good size. There are instructions at mustangworld for that too.
------------------
96' GT
5-speed,K&N air filter,removed air silencer,80mm MAF,Mac True Fit Cat-Back
http://minot.com/~topel/stang9.JPG
[This message has been edited by T-Bone (edited 03-22-2000).]