Who do we like for custom clutch bits?

The Sachs clutches I've been buying for '80s Saab 900 Turbos for nearly 25 years are now junk and no longer hold past stock boost. I've gone to a later, larger-diameter kit but it doesn't help. 

Who's your go-to go-fast clutch source? I have a new PP/disk on hand and was hoping to provide some measurements and power/torque numbers, as while there may be an off-the-shelf kit somewhere, I assume these things are kinda formulaic to put together, and it'd be cheaper if I didn't have to pay for someone's addition of red paint...

Back in the day, I used to go to the shop that took care of big truck brake/clutch linings. 

I was just having this conversation today as I need to get a custom clutch disc and diaphragm pressure plate made for very one off a job I am doing.  I can't imagine too many other folks want a T56 to Ferrari Columbo V12 clutch setup.

In the past I used a small custom clutch builder that was recommended to me. He simply welded my spline into a very crude (like only partially round, hand cut) unsprung disc he made and painted it yellow. It was bad. He also supposedly increased the clamping force of the pressure plate but I am not sure how. Looked like he just painted that yellow too.

Then I used clutchnet who did a much better looking job, but the friction disc had 3/8" of runout. We sent them a video of the wobble on the lathe asking them what to do and they responded by not responding.  Total radio silence, no returning of emails or voice-mail.

This time I think I am going with Spec. They did a great job on a custom T5 to Lotus twincam thing we did some time ago. 

I will call California custom clutch too. I have heard good things about them.

I've had good results with LUK clutches on Nissans and VWs in near-stock applications.  I've also used ACT on boosted Nissans (over 2x stock TQ) with excellent results.

Southbend Clutch. They do custom high performance stuff.