To be honest sounds like may be a cooling problem, ive been tracking for years with Evo's, RS2000's and now a MG ZR to name a few and ive never had a cooling over heat when you moving that fast should easy have enough cooling through the rad etc. Defo would advise fitting a oil to air cooler tho speck to Matt Lewis racing he does loads of kits at good prices i would advise to run a take off plate with a 80 degrees thermostat in to avoid over cooling the oil when driving on roads etc