Excellent headers. No complaints.
On my 2008 GMC Sierra Denali, these fit perfectly. The improvement in power was immediately noticeable. Better throttle response with faster revving with much more rapid acceleration. I had several other mods already on the truck (CAI, cat-back exhaust, programmer), but this one piece really pulled it all together. I'm not sure if the improvement would have been quite as dramatic without those others in place, but whatever the reason, this single component made a marked improvement. Aesthetically, these are very good looking ceramic-coated headers. They take up considerably less room than the stock headers, especially since they don't need the heat shields. They permit more of the internal engine sounds to escape as well, which adds a nice mechanical aspect to compliment the V8 rumble out the back. Installation will vary depending on the truck, and will probably require a lift.