[MaxD]

You can't go wrong buying Nomex underwear from any of the major brands : Sparco, OMP, Alpenstar, Stand 21, etc. All make FIA approved products. SFI is an American thing separate from FIA.

Optimal is two long sleeve shirts, a single long bottom + a couple pairs of socks and a balaclava or two. If you didn't size you helmet with a balaclava it may be a bit tight. Not running events over a whole weekend, one of each is sufficient.

I always wear some form of Nomex under my suit. It is up to 42C here during Utah summers so I have a few short tops and bottoms. Not FIA but I know the risks. I usually don't run a coolshirt unless it is over 28-30C.

The carbon-x and like finishes help a bit with garment funk over a weekend. Don't think it makes you feel cooler.

Tops and Bottoms can be rather pricey. Look for sales over the holiday.

My sizing - I'm an extra husky 5'7" - 195ish guy. Sparco M/L or OMP L Top/M bottom.