I just bought a 2018 denali 5.3 back in december and have a few questions about headers. I'm thinking about getting some long tubes for the truck since i've run them on all of my cars over the past 25 years. However, i'm not too familiar with these new direct injection engines. Realistically, how much power would i gain running long tubes with a catted Y-pipe or custom X-pipe. I would also have this setup dyno tuned at ECS in jersey. I'm just trying to see if the power increase is worth the time and money. I remember picking up about 35rwhp on my 2002 z06 when i did long tubes with a tune and thought that was worth it, so i'm on the fence. If anyone has any videos, dyno plots or advice, i would greatly appreciate it.