Here what I can tell you, You may get a check engine light, this is caused from the cats that were supplied not being efficient enough. ARH may have changed to a better cat since I went through a period of this after I installed them. Nick who owns ARH was great to work with, I was the first to put them on a 19 6.4. Also if you have a 4 wheel drive and are going to tow heavy loads up long steep grades you may want to wrap the collector on the drivers side with some header wrap. The header is getting so hot that they were starting to melt the front drive shaft slip joint boot, Also on the pass side where the hard brake line goes to the rubber line you will need to wrap the header and pull the rubber line back as fare as you can and wrap it. it is to close to the header. I just found this issue a couple months ago and contacted ARH and sent pictures. Nick says they will change the fixtures to fix. So ask if your going to go with the headers. I live in Colorado and tow up some very steep and long grades so the exhaust is getting very hot. Are they worth it? as for power they are amazing, you feel it everywhere. And the torque, under hood heat? has not been a problem. For the other issues it has been a ***** at times. There should have been more testing on the 19 and up trucks, things have been changed in the ecm area and the brake line department as per Nick. ARH is a stand up company and has worked with me on the problems but as for a new header with more clearence have not seen those yet. Just call and ask before you buy. Hope this helps