I don't think I have a particularly hot ST13,,, but I decided to take my inner cowls out, shortly after getting the bike. Like many others,,, I never put them back in. Takes 20 minutes to do. Allows a ton of cooler air to dilute the hot air surrounding the engine. If you don't like the results,,, just put the inner cowls back in, which takes another whole 20 minutes. I have seen some fancy cutout efforts on the cowls,,, and even on the outer fairings, (gosh,, I could never cut my outer fairings). But I can guarantee that filling the inner cowls with holes and a few slots will never flow as much air around the rad, as simply taking the inner cowls out. Do the simple stuff first and see if you like results,,, if you don't, then put 'em back. Also,, for long legged pilots,,, realize that moving the seat up can open up a hot air channel that allows hot air to be sucked into the crotch zone (sing: "chestnuts roasting on an open fire") by the natural low pressure region between your torso and the dash. With my 30" inseam,,, I don't have this problem,,, but I have seen a tank to seat gap blocked up with piece of round foam pipe insulation. Again,,, easy to test and if you don't like the results,,, you are only out 10 minutes work and 99 cents worth of pipe foam. I ride locally with ankle boots and bare shins in the summer heat. So I don't believe that a hot bike can not be cured,,, cheers,, CAt'