I have a gen 2 and gen 3 and both are fine. The gen 3 is noticeably quieter and more refined, but I like both. I had emissions issues out of my 2014 fixed under warranty at 16,000 miles and a dpf replaced under warranty at 101,000 miles. Otherwise it’s been just fine. My Gen 3 has 71,000 miles on it now and it’s been perfect.The gen 1 engines never made it to market the gen 2 is what got used from 2014-2019. The 3rd gen is claimed to be 80% new and so far I have not heard of any major issues.