ALL performance springs have a shorter life, the yellow LS6 springs are only good to .550 lift, so with the TR220 cam you'll really really be pushing them, which will make them more prone to failure. Patriot/PRC released a statement recently claiming there dual springs to have a life span upwards of 50000 miles. With that cam and if you break them in properly (a few heat cycles) they will give you a long life, and with most duals meant for use with .600+ lift it gives you room to grow. Doing valve springs sucks. And god forbid one break you'll still have one holding the valve up.