A couple of times when driving I've experienced the following scenario: I approached a large roundabout in 3rd gear and leisurely take the 1st exit. As I drove down the slip road I change up into 4th gear around 35-40 mph as it has a good speed range 40-60 mph. As the revs picked up past 2.5k I felt a slight hesitation, then the car picked up again, only to hesitate again, to then pick up once more. As this happened on the same piece of road a couple of times I thought the hesitation was the VSA kicking in on an uneven road surface, even though I never saw the VSA light appear, as this is exactly what the hesitation felt like. Today as I was further down the slip road I noticed the revs rise slightly faster than usual. So I lifted off and saw the revs instantly drop about 400-500 RPM before then tracking down consistently with the speed and revs of the car and engine. Up until this point the clutch has always performed very strongly. The usual test of a slipping clutch is drive the car in 5th or 6th gear at low speed, put your foot hard down and when the turbo boost kicks in the load on the clutch causes it to slip. I've tried this several times and only get a strong pull with no clutch slip. I can even generate wheel spin when exiting roundabouts in 2nd gear. I went for a drive tonight and repeatedly tried to make the clutch slip. I can only make it slip in 4th gear under heavy load and only when cold. Once the engine is up to temp I can't make it slip at all in any gear at which point the clutch is nothing but strong even under prolonged heavy load. The strong pull under load when warm leads me to think the problem isn't with the clutch plate but with something else in the system. Any ideas what could be happening, particularly in this gear, or possible adjustments that I can make to try and cure the problem.