If you take a look under the passenger seat you can use the bar that is there just route the submarine belt to avoid the seat release and it works -- no need to cut plastic or make a bar.
The D3s were made specifically for our buggies and Simpson is at the top of my list for safety equipment -- been manufacturing them for years. Hope you never need them but if you do they will keep you in place.
I enjoy their vids, but just like the rest of us, they don't know everything. At 26 minutes, where 5th point "importance" is mentioned, with Sous belted in, his lap belt is too loose (read too high-should be in the "pelvic pocket"), and his shoulder straps are too tight (pulling the lap belt up too high). That condition could cause internal injuries, as mentioned in the article linked above. I think 5th points are more effective/necessary in more reclined seating positions, as found in open wheel road course cars. I agree Simpson is a good choice (offers 2" webbing) as many automotive harness makers don't incorporate shoulder pads, since most auto rules require flame retardant suits, so pads aren't needed. Safety for recreational vehicles, while obviously important, is a compromise between comfort/convenience/safety. I have enough confidence in a properly secured 4 point, in a upright seat SxS, as I do the 3 point/air bag systems in my street vehicles.
No worries, Phm14 we all have our preferences and opinions. I still like the 5 point harness and you can certainly save a dollar or two with the 2" version -- I would still get 5 point and Simpson is my first choice and the extra padding prevents the belts from rubbing. For now I don't plan to run NASCAR, or enter in a auto racing with the SXS so I should be good for now. Again no worries.
I just ordered a set of D3s, direct from Simpson. I verified that their latch will function properly, without the sub-belt fixed. In the early days of racing safety restraints, ~75 years ago, 3" webbing was used for strength. Some racers adapted surplus aircraft harnesses to their cars. With today's tech and materials, strength is no longer a concern. Even DOT cargo straps, with working loads in the thousands of pounds, are 2" webbing. Simpson can do a custom harness, using 2" lap belt webbing, and 3" shoulder belts, if preferred. They have opted not to offer 4 point harnesses (probably due to some lawyers advice), leaving the sub belt option up to the end user. In our litigious society, we all end up paying for CYA. Truthfully, if Joe Public doesn't know how to properly secure a 4 point, he's safer with a 5 point. The article linked above makes a very strong case for 2" lap belts being safer than 3"...strong enough to convince me: they fit the pelvic pocket better, and so can be (tolerated) tightened more snugly than a wider belt. With safety equipment, proper fit matters, whether we're recreating or racing.
I went with IMPACT brand certified SFI spec 16.1 2" belts with cam latch. I have never liked the latch system dis-comfort around the hip and my wife cannot unlatch them easily.
I found G-Force 2" pads. Not too many companies make pads for 2"
Also, I attached neo magnets in the roof and seat area to keep the belts out of the way while entering and exiting