You might want to rethink that 100,000 miles. I've noticed a lot of car manufactures (e.g. Kia) that recommend a change at 60,000. I would not ignore that recommendation.

Timing bits are considered emissions equipment. In California (and states that follow California requirements) this means a 150,000 mile warranty. Most manufacturers will thus specify a change interval that avoids warranty service. Some, like Mazda in the 90s, will use the same belt rated for 49-state compliant intervals and simply bump up the interval.