well, i hope you got scroth belts. cause any 4 pt. isn't going to prevent submarining unless scroth belts are used. if you are not using quality belts, like 5 pt. 3 inch straps, ur 3 pt stock belt will be better!
as for mounting,
check out here, it shows how the manufacturer wants the belts to be routed. sroll to pg. 44.
unfortunately, the only way ur belts will be safer is if you mount them properly, AND use a 5 pt or greater belt to prevent submarining.
also, what bar are you using? and what straps are you using? i'm assuming a codesvt bar? and i'd be interested in the belts your using too.