hahaha I know 24's don't make horse power! the guy who built this setup I guess thought that way. the TB has been changed and I think the piece the MAF attaches to is bigger than 55mm. everyone says spend the money and get a calibrated MAF I've read they aren't accurate. this is my first mustang with EFI
There are meters that are considerably better than others. Pro-M and PMAS are some of the better offerings.
The previous owner probably had upgrade plans that were never realized. The plan that I outlined in the post above is one approach that is relatively inexpensive while still making performance sense. Of course, there are also other ways to do it.
If you hang out in this forum long enough, you will see a couple dozen other approaches to building power. It's not that difficult to come up with a plan of your own that you like.
Regardless of the way you chose to go, it's ALWAYS a good idea to buy your present mod while keeping an eye on your future mods. It keeps you from spending money twice.
So if you decide to buy another Mass Air Meter, buy it for the engine combo that you WANT to have and not for the one that you currently have. It makes future upgrades a lot less painful on the wallet.
Like anything else though, there are limitations. It's easy to purchase parts that are not good for current combo and will not be very good for your future combo as well. It's always best to write it all down, ask questions, and get a good map from where you are to where you want to be.
All of these guys that have responded to your thread are very good at doing just that. Most of them have done it many times over, have made the mistakes, and now know better. What's in their heads can prevent you from tossing money out the window.
Good Luck!
Footnote: I personally, do not subscribe to the idea that ANY air meter with a removable sample tube is a good idea. I avoid them like the plague. Sure... There are folks out there that have them, made them work well, and swear by them. For everyone on of those, I can probably dig up two more that got nothing but headaches from 'budget' Mass Air Meters. In my opinion, the meter is not a good place to save money.