Here's the lengthy post I promised describing my individual experiences with my modifications on my truck (to date 3/13/09)
I'll start off first by stating the obvious, I know not everyone will have the same results, some may be better some may be worse. It all depends on driving habits, geography, weather etc.
When I bought my truck new in 05 my daily commute was approx 90 miles roundtrip to and from work (Savannah to Hilton Head). I averaged very close to 20mpg on that commute and as low as 14-15 in the city. I made no modifications to my truck until I moved to South Georgia.
I moved to South Georgia and started the modifications around 30,000 miles. First I installed a leveling kit and put on larger tires, 265/75/R17's. My fuel economy suffered, dropping to 17 hwy, but I lived in a rural area and didn't do much "city" driving, not a lot of stop and go.
I added my S&B Cold Air Intake kit around 32,000 miles and my fuel economy shot back up to 19mpg hwy. I was pretty impressed. I felt like I had a little more "getup" in the higher RPMs, over 2800-3500 especially, can't honestly say I really "felt" much difference at lower RPMs.
I moved to Valdosta, GA, a small city, and the miles had racked up. At 85,000 miles I was getting about 16 hwy and 13 city. I swapped out my stock muffler for a SI/SO magnaflow muffler. No noticeable performance or mpg gains, just sounded a little better.
At 87,000 miles I added the Edge Evolution programmer. Fell in love. It REALLY woke my truck up, better throttle response. My truck felt a LOT more powerful at any RPM and once my “need for speed” subsided, my fuel economy went back up to about 18 hwy and 14 city.
At 95,000 miles I changed my exhaust setup to true dual Magnaflow exhaust, x-piped with high flow cats. I can't really promise much for performance gains, I'm not sure if I felt more horsey or just sounded like it,
. My fuel economy went up again to about 19 hwy, not much of an increase at city.
Shortly there after around 98,000 I cut out my rear cats (the high flows) The only difference at that point was the sound a little louder, no performance or mpg differences.
Right at 100,000 miles I upgraded to a Gryphon with a custom 87 octane performance tune, right after my 100,000 mile maintenance which included the plug change. LOVE the Gryphon, my throttle response increased, my CAI didn’t sound like a sheep on sterioids anymore and my fuel economy is better than ever! 20.4mpg on my last highway tank and I’m steadily getting 16-17 on my weekly driving to and from work, grocery store, church etc.
I hope this helps some folks, my underdrive pulleys are sitting in the garage to be installed tomorrow and I’m ordering an eFan kit from Troyer today (if Crystal ever calls or emails me back). I’ll update after I’ve got some miles on those mods, planning to wait a while to install the eFans so I can see how each effects my truck independently.
Any questions, comments, or requests for more info I’d be happy to oblige!
Neal