The under-body diffuser has debateable merits - the idea is to smooth the A frame and rear chassis sections in order to channel and speed the exit of air flowing under the car. The aim is to create a region of low pressure to effectively help generate some additional downforce at high speeds.

 

There doesn't appear to be any empirical evidence yet to suggest this is hugely effective, but some racers are using them and people who have tried them seem to be sure that they make an improvement. At the very least they keep the back of the car cleaner!

 

The kit is very simple and intelligently constructed. It consists of one undertray for the A frame and one for the rear chassis section beneath the fuel tank. No modifications to the car are required - Rubber lined P clips fit around the chassis members and the trays simply bolt to the P clips.