Originally Posted by itchy b

yes, you must cut holes in the windows for air flow otherwise the engine will build up too much heat!
here's a couple of pics of what i mean.
60mm hole in the front window for legal size. ( I cut mine into the centre of the front window to balance the airflow around the car)
double the size of the front window for the rear one.
you can also cut out the front side windows too if temps where you live are high.
P.S. Make sure that all the corners of window cutouts are round , not square as the cracks / splits usualy start at a square corner of the cut out
Sory to post my Mugen photos but these are the only ones i have that show all the window cutouts