I installed Amsafe inertial reels in my RV7A. I'm not sure they sell to experimentals anymore but I really like them. If you use the supplied cables then the inertial reels will be forward of the baggage bulkhead and flop down many inches. In a crash they will very likely not lock at all before your head hits the glare shield.
To fix this I had West Marine make me up new, shorter shoulder harness anchor cables (at the suggestion of Vans tech support). They attach to the same place the originals do on the longerons behind the baggage bulkhead, but in order to work correctly inertial reels need to be hard mounted in the correct orientation so there is no slack.
I made a slot in the baggage bulkhead, fitted an aluminum angle across the fuselage and then mounted a small piece of steel to the angle for the inertial reel to sit on. The piece of steel plate penetrates the baggage bulkhead such that the inertial reel sits on the forward portion, then the baggage bulkhead with the angle directly behind it, the middle of the steel plate has the mounting hole to sit on the piece of angle and the aft portion of the steel plate has a hole to mount the anchor cable clevis which then leads back to the traditional mounting on the longeron.
The only other adjustment I made was that I slotted the hole in the steel for mounting the plate to the angle at the baggage bulkhead and only tightened the fasteners enough that it would allow the plate to move slightly fore and aft. My reasoning (I'm no engineer) was that it appeared that, after any seat belt and cable stretch, the crash forces were designed to be transmitted through the harness and cable back to the longeron. I didn't want to alter that by cinching the belt at the baggage bulkhead and risking the fuselage buckling inward there, if it wasn't designed that way.
I really like the ease of movement that the inertial reels allow.
RV7A "Stella Luna" ECI IO-360 WW200RV Pmags 360hrs
VAF 2018 paid plus some for those who can't