On those RRs, even if you give it a bootfull the DSC chops in and overrides your wide open throttle to maximise traction (as it sees best).
I have had a similar problem in deep sand (before I read the manual) where the engine feels like it is dying due to DSC. When you turn it off you can spin the wheels like anything :D.
Glad to hear it is probably just his tyres.

