I run my 01" 4x4 supercab(5.4) in Colorado at 7300 ft and have a borla single 3in exhaust and a MAC Cold air induction.I also had a Diablo performance 3 way chip installed.She runs great and the only other add on would be a good header system I've read the posts on JBA and GIBSON- a long tube would be much preferred - is the Gibson considered a long tube or just Dynatech and others like it?Does the 4x4 with its 90 degree pipe turn before the CAT really benefit that much with headers???--I cant find any real info on this particular application... Thanks