Here's a link to the inner workings of the US Yamaha 600cc Legends racecars.

At $3,899.00 that works out at $6.50 per cc.

I assume it has some ungodly power output and weighs the same as a large box of matches?

Either that or the rocker cover is platinum inlaid with diamonds perhaps

I'm not an ardent follower of that race series and only briefly looked at the site, so I'm not sure of the output of their engines.
It was the links on the left side of the page that I thought may be of interest.

I *seem* to remember for comic relief or some UK televised charity event they had some celebs racing various cars inc. these (if not these then something bike powered and very similar). They did indeed seem pretty quick, but the celebs were very rough on the gearboxes and 2 or 3 of them didn't finish.

I know there's only one way Jodie Kidd could persuade me to let her drive my car

There's a national Aussie Racing Cars (used to be called Legends) series here which runs as a support series to the V8 Super Cars.
They're different in that they run 1200cc Yamaha aircooled (FJR/FZR?) engines.
They are awesome performers and make a mockery of some of the multi thousand dollar race cars.
They're well sorted and absolutely bulletproof.
Some of the body styles are really cute too.