Hello, I am in the process of installing a 6.2 in a custom truck.Are the 6.2 hummer headers any gain in power/mileage.custom building the exhaust so thats no issue. thanks Dave

Check the fit to see if it matters. My C1500 didn't have the clearance needed on the driver's side - the steering was in the way. On the passenger's side, the frame rested on the manifold - so that was a no-go also. It sucked, but I gave up on using them and bought some 6.5 manifolds. They do NOT appear to flow as well, but they fit and gave me the needed clearance.

The freer flowing exhaust the better, the Hummer headers should flow more than the stock ones but probably not that significant unless you plan to utilize the larger exhaust outlets.

They make a HUGE difference. Some models require mods. I found on my van, the passenger side fit with no mods but I had to reangle the outlet on the drivers side.

http://www.dieselplace.com/forum/showthread.php?t=147364&highlight=header