I recently installed the smaller supercharger pulley from Mini Mania,
along with plugs and a new belt. It feels great now.

If anybody needs to borrow a belt detensioner tool, I would be willing to loan it out. Im in the SF area.

Overall, it took me a while to complete the swap. I spent a bit of time just tying to get the stubborn oe pulley off. I would recommend using a sacrificial screw in the supercharger's pulley shaft. If I were to do it again, it would take less than half the time, I hope.

I cant really tell if I gained 20hp at the wheels as claimed, but it is much quicker regardless.

I will be trying it out at Laguna Seca this Dec with the alfa club.
In case you're interested:
Laguna Seca Double Trackday