saleen and roush are a seperate company that alters mustangs and other cars. saleen and roush are different from a gt for what they add. the stage 1 roush are only different in apperance.while stage 2 has added suspension and stage 3 its a supercharged.
saleen comes in seperate modifications. it can be a regular v8/cobra with just a body kit and it can be supercharged with add breaks and such.
theres roughly less than 1k saleen made ea years before 2005. 2005 and up i believe theres ~1.5k saleen made per year