Greetings. I'm looking for a set of drill bits, like this, for drilling out tough bolts, such as hardened exhaust studs. (Even with my favorite dewalt HSS drill bits I often have a really bad time getting anywhere.) I've read a few sparse comments about solid carbide bits being great but I never used them, and I can't find sets of them anyway. Are they worth the price (like $25-40 a bit)?