Bill,
An intake as a stand alone system may not make a material difference. However, in conjunction with a good exhaust system the end result may produce more that than the sum of the parts alone.
As for the K&N, I also had a K&N FIPK in my Tundra and it was loud! That's why this time around I ordered an AirAid Jr. which retains the original air box. It has a high flow replacement filter and a less restrictive MIT. I also got a throttle body spacer as well. I bought these for my Yukon and I'll let you know how it goes.
At this point I only have th stock exhaust but I am hoping for a better throttle response. Kacy
http://www.airaid.com