Yes they are serious and yes parts and tuning have become difficult to acquire. This will probably be the most info you will be able to obtain in here related to this subject. Your best bet is to find a local diesel performance shop in your area and talk to them face to face and see what they can do. A lot of folks are paranoid about letting out anymore information on the internet pertaining to this, especially to a new forum member. Best of luck, it is becoming a thing of the past.
2015 GMC Sierra 2500hd CCSB 4x4, Edge CTS2, 4" DP back, turbo resonator delete, EGR blocker plate,Bilstein 5100s, 10% tint