I contacted the seller with a few technical questions about how they made this new pulley, and he responded with more info. than I expected. Here is the response I received:

"The 65mm pulleys have thickness issue inherited from its original form; the OEM. It is essentially an OEM pulley with modified grooves. Not a whole lot of engineering going on. The 65mm has a wall thickness of 2mm and can't go any thinner. The Karmen pulley is a new born. It only uses the OEM as a reference for fitment. It is designed to use smaller bearing ***** for increased speed and with smaller bearing outer diameter. This leaves the wall with plenty of thickness to work with. The inner bore of the Karmen pulley is 47mm and the outer diameter is 62mm. In radius they are 23.5mm and thickness is 31-3-23.5=4.5mm.
Problem Solved. The idea here is simple. To make the pulley smaller, we just have to reduce the inner diameter! There is also an issue with bearing speed. The original bearing has a higher load rating but limited speed. Smaller ball bearing has higher speed rating. The bigger the bearing, the lower the RPM at the same distant traveled.
Warping and Wobbling: The Karmen pulley doesn't cut corners by using AC compressor clutch plates that are in production to cut cost. These AC compressor clutch plates(armatures)have a strong tendency to warp and cause wobbling or rubbing against the magnetic clutch.
The Karmen pulley is made in the USA."

That said; I'm also looking forward to Rudy's findings.