Pretty darn sweet if you ask me - I remember seeing this advertised in a 1996 issue of MM&FF (still have the mag) and it claimed to have gains of 47 hp. Requires a custom hood (also offered by Roush once apon a time) The list price was like $2700 (included hood). I'd bid on it but I have no intentions of getting a different hood (not enough funds right now) Pretty sweet piece if you ask me! Rare for sure!
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2461271454&category=46098
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2461271454&category=46098