Seat-belt tightener
Adding seat-belts to your cockpit chair can enhance the flight simulation experience. The fact that you are strapped-in, make the motion platform movements more pronounced. You can further enhance some in flight feelings by manipulating the tightness of the belt in certain situations.

During deceleration, especially during braking on the runway, the forward forces on your body can be considerable, and you would feel yourself being pushed into your seatbelts. Since my platform has limited tilt, this feeling is not very pronounced. Therefore I added a seat-belt system that will tighten the belt when the platform tilts forward.

The system is very simple: Strings with springs are attached to the seat-belt tightening points. The other ends are fixed to the floor.  When the rear of the platform lifts-up, the strings will stretch the springs, and the belt is tightened. This is shown in the drawing below.

The seat-belt is a 4-point type, therefore I have attached the spring loaded strings to the top and sides of the belt, to make sure you feel the belt tighten all over your body.

4-point belt                      rear view                            detail of belt tightening on the sides.

This video shows the system in action. I did some adjustments to make the strings start to tighten the belt when the platform forward tilt is about 40% of max. Tightening force at max is about 5 ~ 7kg per point. 

The experience:
Deceleration is indeed more pronounced, and the landing of a 737 with full reverse thrust and braking is definitely more realistic. It must be noted that positive heave will also affect the belts, but since these are short bursts, they actually feel quite realistic.