When to get a new clutch?

The clutches on our cars are kind of ''hit or miss''. I've seen clutches on stock cars go bad at 2500 miles and clutches hold up a while at over 500 rwhp and that's no bull. I would just get the power adder and plan on the clutch package when you have the cash or do it right away....whatever you can swing. You will either feel it start to slip or have mechanical problems when it goes, but I would definitely plan on spending the money, so just put it on the list.