Looks like a good modification if you are having trouble with the side belt. Good Work!!!! Sorry I couldn't help with the belt problem. But I am still wondering why your belt slipped. I don't have a tentioner on mine and it works great. I have never had to change out the rear or side belt yet and I have had my car fora year this July. It seems that all parts are not machined the same way. Some part my be shorter; longer; or not wide enough to fit properly. But, good job on getting the problem worked out!!!