Yes, there are quite a few.
However, it is a somewhat dangerous game.
Far far safer to supercharge a 5.0.
The GT350 engines have enough trouble without adding 300+ hp to them.
Also, the GT350 is such a good drivers car, added a bunch of power takes some of that away.
The cars certified fuel mileage on the base car is without the gurney flap.
The CFTP car certified fuel mileage is with the wing in the “street” setting.
The base GT500 will get significantly worse fuel mileage with the gurney flap installed.
They only put that in the manual for legal reasons.