AMSoil is a good synthetic to use. I use it in my 01'. To say that I've noticed a substantial difference would be a stretch. But I like to think that it's working.

The K&N intake system and filtration system works pretty well. I've been using it on my rig for the last year and a half. I've not noticed a significant increase in mpg. There are other filters out there that prevent more junk from getting into your engine. If you look and search through the forum you'll find the info you're looking for. These guys have discussed a number of times already.

my 2 cents for the day.