ARH - Long Tube Headers & Y-Pipe (99-06 Full Size Truck 5.3/4.8L)Horsepower Torque Great Sound and a dose of added Fuel Efficiency is what you'll get when you combine ARH's high quality, 304 S S header systems with your 1999 2006 full size GM truck. Manufactured in the U. S. using only U. S. made materials, ARH's GM truck systems feature 3 8" thick laser cut flanges with hand ported inlets, merge collectors with scavenger spikes, 200 cell metallic substrate cats and your choice of 1 3 4" or 1 7 8" primaries.