RE: Need some help with SCARY ASSERTIONS of FACT
OK, JV. Don't take it personal. You might not have recognized it, but my statement was one of my opinion. I do, however, appreciate that you generally hold my opinions in high enough regard to confuse them with factual Truth, but that isn't really necessary.
My belts are installed directly behind the seats. I have seen manufacturer's recommendations as well as read enough to be aware that belt stretch is an area of potential injury. My car is built with the belts short...to each their own, this is after all a sport where you're ultimately responsible for how you get home; in your car, in a Death Star, or in a box.
For what it's worth, standard restraint and impact survival systems built into your production car are engineered to prevent life-threatening injury at 35 mph frontal impact, not more (arguably, in higher-end German sports sedans/coupes, the engineered safety margin is fairly high, one source quoting 40% excess capacity in Audis; but this is not typical of the average production car since it isn't legislated). In a 35 mph impact, that 2.5" single diagonal belt stetches enough that the face WILL hit the steering wheel when the driver is correctly positioned with hands at 9/3 or 10/2 position. Not my opinion...fact (I've tubed enough crash victims in my past to be aware of this, not to mention discussed this very issue with an automotove safety system engineer). The explosive in the steering wheel, to paraphrase Conrad Zumhagen (the engineer), doesn't save your life, it just keeps your face out of the steering wheel.
So, I look at those two 3" belts as giving me about 120% more restraint capability than the standard 2.5" diagonal belt. Of course, my closing speed on a frontal impact will probably be under 35 or 40 mph, but it could actually be lots more (even my ancient machine will see 85 or 90 from time to time). Decellerative forces increase by the square of the speed, so it's not to much of an intellectual leap to reflect that in a 70 mph impact, those two 3" belts are potentially going to stretch enough to put my face into the steering wheel; the less belt, the less stretch, the less likelyhood of impact. OK, so that's a matter of conjecture, but I don't care to do the destructive testing in the rally car necessary to really prove my point. Conrad does, with production systems, and gets paid for it.
Back to the original issue, I would like to know what the data is to show that stock mountings (again, with fasteners in full shear) is stronger or safer than well-considered custom mountings taylored to the car's shell and seat installation. JV's comments notwithstanding, the belt length just looks to me (this is my opinion, for those not comprehending that fact) is a bigger safety issue than the pre-2003 anchoring requirements.
Just out of curiosity, I think I will run these questions by my engineer acquaintance......