I've bought 440 source stealth heads back in 2009 or so. Ran for a year than upgraded to 10 degree locks. Around 2014/15 or so than had them hand ported and new valve springs installed since I had 3 inner springs that were broken. Ran them another handful of years til I Bought a set of Trick Flow 240s in 2019. My dad bought a a set of Trick Flow 190s this past winter. We've also had 2 sets of small black Edelbrock RPM heads that have been issue free. We do give the heads a good visual look over, but don't tear them completely apart. We go to 20+ races a year so we run our stuff. Would it be a bad idea to tear stuff down and check out everything out, absolutely not, but I'm sure there's more guys that bolt them right on than have them checked out.