Ford has released an upgrade for the standard Focus RS after special edition RS 500 sales surpassed expectations.

The Ford Focus RS 500 sold all 101 models produced for the UK within seven days and Ford says it could have sold five times as many.

An MP350 kit has been introduced for the Focus RS, allowing drivers to upgrade the 305PS engine to 350PS and give an extra 20Nm of torque.

The upgrade fits an air filter box, larger diameter exhaust downpipe and higher-capacity fuel pump. The software has been upgraded to cope with the improved performance.

Mark Simpson, Ford Britain Marketing Director, said: “If you couldn’t get an RS500, which sold out within seven days, this is the next best thing."

The upgraded model will not have the interior features, matt black paint and RS 500 badging as the original, but will deliver similar performance figures.

An MP350 kit will cost £1,995 and will not void the warranty on the Focus RS. This compares to the £35,450 Ford Focus RS 500, which sold 500 models worldwide.