Might be a stupid question but do you run with the A/C off? I would check that. My E90 got hot really quick on the track the one time I forgot to turn off the A/C.
I use water/iso alcohol in my E46 as a charge cooler. Meth will do the same thing and allow everything to run cooler. The thing about meth is not the easiest thing to find and its not cheap. I use AA's old water/alcohol injection system. So I go to the store, $2 bottle of iso alcohol and $1 gal of distilled water. Good to go!
The bonus is if I get a cut, I can use my w/a system to clean my wound!
2013 F30 328i Melbourne Red
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red