Who can know? No one's hit 100K miles yet, and there are many ways to define "highly modded". Obviously you can push a car past its design parameters and shorten life (as an extreme example, race cars typically last a couple hundred miles between major overhauls), then again you can totally abuse a stock car so that it doesn't last 10K miles, whereas a highly modded car with the right kind of care can last a really long time. Climate counts too, California/Arizona is better than Michigan, for instance.