I'm hoping the Pista owners here can help me out.

What are my options for 1" threadless stems? I'd prefer one in black. Can I purchase a universal shim so I can fit a 1 1/8" or do I need to find one that comes with it?

any 1 1/8" stem can be shimmed down to 1"

always liked the cinelli alter stem, but it's not made anymore, so you'll have to comb ebay, etc.

3t mutant.

ITM chromo at icyclesusa.com. 1"steerer/25.4mm clamp. "10

3TTT mutant is nice. I rode it for a about 8 months, nothing to complain about except I wanted a greater drop then 80 degrees. I just switch it out for the Cinelli Vai. It is:
Black anodized 6061 T6 aluminum
Fits 26.0 handlebars
28.6(1-1/8)fork clamp dia.
Angle:+/6 degree (50mm, 80mm)
+/-17 degree (100mm, 110mm, 120mm)
190g (11cm)
https://cgi.ebay.com/ws/eBayISAPI.dll...category=42333

*edit: when I bought the stem, it came with the shim

I've had a coupla Mutants and they look about like a half flacid (or half erect I guess depending on if you are an optimist or a pessimist) penis.

I've got a 90mm Titec stem I used to run on my Pista. It's dark grey instead of black but if you're interested I'd sell it to you cheap as I got rid of the bike and a 1" threadless stem is pretty much useless. PM me.