[squirrel_hunter]

I've only ever seen it as a Fireblade seat unit (the plastics) on race bikes. I think its a stock subframe that may need modification or a special race unit. Personally I don't think the lines look right with the rest of the bike. However, there are lots of Fireblade models so a different one then I'm thinking of as I'm not a Fireblade expert might fit.

My recommendation, find one for sale in a local showroom and approach with a tape measure...