Everybody lost sight of the original question. K&N has two models that will fit the Tahoes. The K&N 77 series intake has a metal tube; the other does not. I have the 77-series installed in my '07 and I chose it for that extra shiny factor in the engine compartment. After installing it, my engine gives off more "growl" when stepping the gas to get to highway speeds. Also, according to the DIC, my MPG went down, too. Yeah, I've been good at not mashing the gas too much, especially when the wife drives it for a week, the results are the same. I saw combined hwy/city driving to be 15.8 mpg vs. 16.5 with the factory intake. Last week, I decided to experiment with premium fuel. Since then, my mpg shows 13.5. All my numbers so far are based on the computer. So, I need to verify them by doing my own math, but it does seem very strange that the numbers would drop so dramatically.

 

K&N claims the intake system you installed is "Guaranteed to Provide more HP and Increased Acceleration." Gas mileage is the tradeoff.

 

Exactly. Power is produced by burning the gas. More power means burning more gas or the same gas more efficiently. Also K&N notes the increased hp is up around 4,900 rpm. BTW premium won't do anything except drain your wallet unless you use a programmer that requires premium.

 

The 63 series apparently offers more horsepower

63
17.54 HP @ 4917 RPM

77
12.49 HP @ 4917 RPM

So what about the 63 series instead? Sure, it doesn't offer the shine but it "apparently" has added horsepower.