I think there were 3 Boss Shinoda's made in 1994 with somewhere around 900HP. I forgot what engine they had but Motor Trend or some magazine once had an article about it. The tires would actually melt and the rubber tracks it left would flame because of the massive amount of power. They said there were major reliability issue though. Anyway, if it was a real Boss then you'd probably hear it. I can't imagine how loud 900hp american muscle power must be.
all of the Boss mustangs I know of (that are real BOSS) are v-6s... and just have the badging on it... that's the whole speciality of it! I couldn't believe it when I saw Boss, and a V-6... it's like that new ricer Saturn (some things just don't go together...)
There was one Boss 604 made by Ford as a show car in 94 to show off the new sn95 Body the engine originally was a Boss 429 converted to EFI by Roush industries and the appearnce was done by Larry Shinoda this car was in Motortend Jan 1995 it has been in several other mags in the last 10 years also and at many shows around the US and Canada The Boss Shinoda Mustangs are version of this car you can purchase from Tam Shinoda and yes you can order it as an appearnce only package or a performance package and there are more v8 cars then v6 cars a complete list of cars and those that are certified are at www.teamshinoda.com and click on owners list.