In my view, Saleen is a "manufacturer" only as far at the S7 - the Mustangs don't count. This is based on the VIN numbers of the Mustangs they modify: if they were a seperate manufacturer, they would have seperate VIN numbers, apart from Mustangs. But they use the same VIN codes as Ford does, so they're not a unique manufacturer (all 2005 Ford Mustang, Roush Mustang, and Saleen Mustang VINs begin with 1ZV).
I think it's my life's goal to find out whether the S7 can in fact go upside down at top speed.