I had similar issues when I fitted a GRS with twin fans to my S2 track car, tried MSD fan switch, 72 deg stat, cut front bumper, bonnet on rear raisers and foam packing between rad and IC, also ran a turbo pre-rad and water wetter. The fans were running nearly all the time and took ages to cool the engine.

After 5 mins on track the water temp was about 110 and oil temp even higher (the hotter water had a big impact on my oil temp and pressure (dropped by 15 psi).

I ditched the front mount and went back to std IC and every went back to normal (85 deg), the fans now only run when stuck in traffic or when coming off the track.

ACTs may be back up to 50 odd deg (as apposed to 30 with GRS) but can has withstood 5 yrs of tracking at that temp without any probelms.