K&N Stock Air Filter replacement?

[kacyk]

Observations on a 5.3 Yukon with Airaid Junior and Airaid Throttle Body Spacer.

Last week I installed both units in the Yukon to be my "test" vehicle before doing anything on the H2. Prior to this I installed a K&N FIPK in my Tundra and found it to yield no noticeable increase in either MPG or performance.

1. Installed the Airaid Junior kit which consists of a new "high flow" MIT and Filter. Unlike the K&N FPIK, this retains the original air box so the sound is not obnoxious yet it does raise the decibels slightly at full throttle. I actually like the sound as it is reminiscent of a 1950’s muscle car. As for the power? I actually experienced a decline in power throughout the midrange. I can’t give any dyno figures but it feels more sluggish than with the OEM setup. Perhaps I expected too much? Not really as I had the same experience with the K&N FIPK. So why did I buy it? Well, I can return it for a full refund and there’s always that glimmer of hope that a different application might yield better results.

2. With the Airaid Junior in, I then installed the Airaid Throttle Body Spacer. Okay, now this made a DIFFERENCE! The throttle response was quicker, the sluggishness went away and highway passing is now a breeze, even with all seven of us in the truck! I’m not sure if all three mods work together of if just the throttle body spacer alone would yield the same results. But there is a definite difference. Any down side to the Airaid Throttle Body Spacer? Yes, an annoying high pitched screeching sound (same sound as faded brake pads on thin rotors) at 2000 RPM. This “screech” according to Airaid is “normal” on many applications. No amount of “perceived” power increase or quicker throttle response is worth the mind numbing sound. Since my Yukon cruises at 2000 rpm, I am returning everything! How unfortunate!