I use the ACE on my P25 and required a 2mm spacer. Gadfly, I emailed you my measurements on the ACE did you not get my email? I also emailed MD and asked the same exact question about the Spacer just in case I was wrong. They told me as well 2mm spacer for the ACE. Does that mean that the Rega carts are 13mm tall, did you ask them?