The Caterham Seven is 50 years old this year, and as part of this weekend's birthday celebrations, Caterham's just unveiled this seriously extreme X330 concept.While it might look similar to pretty much every other Seven since 1957, the X330 could be the most extreme version yet.It is based on the CSR, introduced in 2005 and with its independent suspension the most significant update of the Seven in its lifetime.The standard CSR's 2.3-litre Ford Duratec engine produces a whopping 260bhp – enough to give the car a power-to-weight ratio of 456bhp per tonne – but that wasn't enough for the X330.As the name suggests, the X330 packs 330bhp, due to the addition of a supercharger. Torque is 220 lb ft – 20lb ft more than in the CSR 260.The X330 is also lighter than a standard CSR, thanks to the use of lighter-gauge steel for the chassis.Carbonfibre has been used where possible to shave yet more weight, and the gearbox is a lightweight six-speed manual.A spokesman said that there are currently no plans to put the X330 into production, but that the engineering concept shows where Caterham is going.If you’d like to see the X330 in the metal, it's at Donington Park in Derbyshire this weekend, 2-3 June, where Caterham is celebrating the Seven's jubilee with a weekend of racing and driving.