Sean Mills, of Big CC Racing in Berkshire, UK, has a serious claim to the world's fastest street-legal motorcycle after rider Phil Hall used his variable boost, stroked-out turbo 'Busa to hit 271 mph (436 km/h) at the recent Straightliners event at Elvington Airstrip.

Suzuki's Hayabusa stands to this day as one of the great achievements in motorcycling. A bike so fast out of the crate – the 1999 model did 194 mph (312 km/h), straight off the showroom floor – that it scared the entire Japanese motorcycle industry into making a famous "gentleman's agreement" to stop competing on top speed.

Even more remarkable was just how massively over-engineered it turned out to be. If its performance was silly stock, it could get completely maniacal with a few modifications, and the engine block was quickly found by drag-racers and land speed record hunters to be capable of dealing with obscene amounts of turbo boost and horsepower.

While early models "only" made about 160 hp at the rear wheel, you'd frequently see boosted versions getting north of 500 ponies – and it seems as mad as those numbers were, they're little league next to what Sean Mills has done with his.

This Hayabusa runs a fully drag-kitted motor, beefed up to 1,547cc and turbocharged with an astronomical 45 psi of boost. It makes almost 1,000 horsepower, which was a stupid enough figure when we first heard about those sorts of numbers on a Bugatti Veyron. Such numbers have no business being anywhere near a motorcycle.

Nobody told Mills that, though, so he went ahead and built a streetbike out of it. Not a stretched-out dragster, not even an extended swingarm straightliner, a streetbike. One that even a relatively well-trained eye would struggle to pick out as anything special at a distance. If ever a Suzuki Hayabusa – well known as one of the fastest bikes on the planet – could be described as a sleeper, it's this one.

Mills gave this terrifying machine to drag racer Phil Hall to have a crack at a top speed run at the recent Straightliners event, and even reduced the boost to "just" 21 psi and dropped the power to around 6-700 hp to make sure it was at least a little bit rideable.

The result on a flying quarter mile across a terrifyingly short two-mile (3.2-km) runway was a timed average of 271.821 mph (437.453 km/h). This on a bike with a number plate and UK tax disc. Take a look at a video below, as Hall short-shifts his way to 200 mph (322 km/h), then hangs on like mad as he struggles to keep the wheels in line for the rest of the run:

If you want to see an identical engine wound up to maximum boost and smoking the back tire on a terrifying dyno run, check out this story from Visordown.