Mine has done something similar at about 70mph in 4th gear i went to accelerate and it just juddered as if i was in too high a gear untill i dipped the clutch and tried again,it is very intermittent and i never get a fault light come up,the dealer could not find anything wrong. Will be interesting to see what your dealer says.
Ha, Funny day for me. Spent best part of £30 going back down to the place, Where he plugs the computer in. Does some laps round his industrial estate. Tells me he carn't get it to recreate the problem and my car is running fine with 0 knocks in the knock bar. And boost and everything looked fine.
I replied " Well its not going to do it round here at 40mph, It was from 70-90mph"
Basically i got nowhere with it. In fairness to the guy I understand he carn't fix what isn't happening.
Laughable part started when I rang revo directly as the guy I went to failed to mend anything or find a problem.
Basically he tells me he's heard of the problem before off people. But whenever he's had people over they've failed to get the car to "missfire" or whatever is happening "Despite people making out it happened everytime" he hasted to add.
Basically told me it was my car. I pointed out my car did nothing of the sort beforehand. Response i got was high boost causes a backlog in the exhaust or a shortage of air intake. Or badoil round the turbo. Tried implying I needed it servicing.
In short i was told there was no point bringing it down for them to look at unless i was 100% sure i could get the car to do it. So im left with a remaped car that doesn't work as it should and they are not prepared to look into it further without me going and showing them 1st there is a problem!