I've tried multiple set ups, forward, backward, belt (reverse tension), vr, mornitors, with/out light... etc. And I agree with all of the comments above.
At the end of the day, it all comes down to what cues the user is looking for when he is on the rig, both physically and visually, and how his brain process them.
I initially had the surge moving forward when braking (no belt), it feels nothing to me. The +/-75mm travel just isn't enough to produce the kind of g-force that you would feel at high speed. Then I added the belt and it started to make sense with the added tension on the shoulder and waist. However, I get motion sickness due to the visual change in the ambient messing up my brain. Then I switched to VR (my default) and re-tuned everything... etc.
At the end I settled with backward when braking and add a little bit of pitch down, plus the seatbelt linked back to the surge actuator so it (passively) adds tension when the surge (actively) goes backwards.
After playing in VR with this set up for a while, I switched to triple with the same set up. This time I switched off all the lights in the room and it feels great!