Originally Posted by PAUL S

Its come to light in recent years that many of the top teams both in the UK and Australia were using a tampered with version of the t4. Basically the bodies were sectioned in two, the flow paths radically modified and then welded back together so that they still looked stock.

So comparing a normal RS500 spec t4 to some of those used on the race cars is not comparing apples for apples with regards ultimate performance.