This is Paula from Alpha Aviation.
It really is a pretty straight forward installation. As noted above, from time to time the pilots side can be a little tougher, but not impossible in 99.9% of instances!
INSTALLATION OVERVIEW
The shoulder strap upper attachment points are created adding MS27405-6 clamps to the fuselage tubing structure adjacent to and aft of each pilots outboard shoulder.
The design of the shoulder strap upper attachment is similar to that provided by Mooney on M20J aircraft; Serial numbers 24-001 thru 0083 and 24-0085 thru 0629. The installation is accomplished through the installation of the attachment hardware to the existing 4130-chrommolly-fuselage frame, without modification.
This installation is considered by the FAA to be a MINOR CHANGE and requires no FAA approval. See FAA – Policy Statement ACE –00-23.561-01; Dated September 19, 2000. If you'd like a copy of this, please email me at paula@alphaaviation.com and I'll shoot one over for you.
Our MOONEY REPLACEMENT/UPGRADE page includes photos, installation overviews, etc.