[Perfectlap]

I had mixed experiecnes with Kuhmos in the past. They came with a set of BBS wheels I bough barely used. Big flat spotting issues with the Kuhmos, VERY annoying. And they were maybe the worst street tires I autcrossed on. Parlticularly in heat, broke loose easily. Not so great in the wet either. I might by them for a corolla or Kia but certainly not a Porsche unless I was a newbie autocross driver. No sense in shredding an expensive set of tires through trial and error.

Unless you are going through more than one set of tires per year I don't think tires are an area you should be cutting corners on. Better to save $400 in some other area of your budget or sell some of that stuff we all have lying around the garage, attic or closet that you never use.
Tires are maybe the most important item on your WORLD CLASS sports car. The difference between a $500 set of tires and $900 set is HUGE. Think about all the other areas of your life where you will end up spending $400 during the course of the year. Putting $500 tires on this car is like buying a high end Nakamichi stereo and hooking them up to computer speakers.

If Michelin are too expensive try the Goodyear Eagle F1's. They are about $100 cheaper and are just as good, excellent in the rain. Some of Pirellis are also good as expensive but durability with that brand has always been a problem for me.
Great winter tires though.