Note that you can't "just drop them in". Lifters need to be prepared before installation or they will prematurely wear themselves as well as the cam. To break them in, you should coat the wear surfaces on the cam and the lifters with a good quality cam lube. It is kind of like a thick special purpose grease that eases the break in and allows the new lifters to conform to the camshaft. Note that even those who plan to reuse their existing lifters need to be very careful about making sure the old ones are installed in the same place that they were removed from since each lobe is unique.
The old school of thought is that you should also submerge the lifters in oil overnight prior to installing them. Hydraulic lifters are actually small pumps so submerging them in oil and allowing them to fill up primes them. Having said this, I have seen more recently that a new school of thought has emerged that says you don't need to fill them with oil since the pressure from your oil pump will quickly fill them anyway. Despite this, I always pre-fill them and have never had a problem.
HTH
Todd