What are you guys using to do the compression and leakdown tests? Did you modify one to work with the MINI or is there one available to will work? It sounds like you modified one. I'd love to see some pictures of what worked for you.
Thanks!

 

I found this compression gauge kit at Auto Zone that allows you to see your gauge from behind your steering wheel which is important because you can see how far the needle moves each compression stroke which in itself tells you volumes about the sealing quality of your cylinders, another plus is your can get a better seal using the long T-shaft that allows you to tighten it better than using a rubber tube with threads on the ends.

You can see my gauge and T-shaft here, you can pivot the gauge 360 degrees even while pressurized.