Just out of curiosity haha
Could you replace the M90 supercharger with an M122 (found on the 2007 Mustang Shelby GT500)?

I remember seeing a forum where some guy said he bought one for his GTP

Do you mean an M112 (probably). There are a few guys running them. It takes a bit of custom work or a kit or two for it to work. It'* been done and can be done though.

John F from Conn Club GP had one on his car. Looked awesome and talk about a fast car (what I hear, he'* demodded for the GTO since).

Go have a TON of supporting mods to do first in order to need or support the flow of a M112. It isn't a plug/play works-on-anything mod. It will not automatically produce gobs of power on any car.

For starters, you won't be wanting stock cylinder heads with it.

and its not the same charger as the Fords uns anyway.....

its the MP112, and the 3800 Vendors are not offering the Kit anymore

The MP112 is the race version of the M112 found commonly on the cobra and lightnings.

From what I can see, unless there are hidden differences, the only difference between the M112 and the MP112 is the outlet. That is, at least, the most significant difference I can see from diagrams provided by Magnuson.

I saw one M112 GTP in person and it appeared to be next to impossible to tune right.

Don't get me wrong it hauled tail, but seemed unreliable for daily driving.