Just to let you know folks - I have been working on the upgrade kit, with a few improvements: 1. Trimmed down the weight, now a complete flipfast weighs only 9g more than a regular angle adapter 2. New internal spring setup means there is no longer any need to pre-drill angle adapter. Now it can be fitted in under a minute, with no tools needed. 3. Cutting longer screw threads has meant that it no longer needs a spacer, which brings the lever closer to the body of the angle adapter. Even more useable.