I bought the 6637 kit for better airflow for my new Stage 1 KC Turbo I also bought here. Kit very easy to install and fits nicely behind driver side battery. I went with the Donaldson Blue, from what I’ve read, these are better than the original 6637’s.
As everything I’ve bought here, shipping is very fast. I did buy 2 as recommended and you can hear the flow when you mash it !

Great filter great kit every minus the clamp drops in super quick it takes all the guesswork out other than the optional clamp, I hope riff raff can keep selling parts everything they do is top notch and I love supporting these guys

Fits great and easy to install. Made a noticeable difference in power and sound

Ordered with the Donaldson filter and filter cover. Easy install. Fits good. Runs great

Working perfect

Simple alternative to the stock filter box with more airflow.

Quick easy install, parts appear to be of good quality. I will probably get the stand-off mount to get the filter off the inner fender. I do have a slight drone at low rpm/light throttle. After a couple days I don’t really notice it unless I focus on it so not that bad. Great product though as far as smiles to dollars go. Made it so I could hear my turbo with stock exhaust, with a slightly noticeable increase in power/throttle response.

The process took about 15 min's, I am very pleased with the performance. Just the filter kit alone really improved the way the old 7.3 responds, now the engine can breath.
Thanks Riffraff for a quality product at a great price. I recommend the filter kit and the prompt service

You could install with a straight piece of 4” tubing like in a super duty, but because of the orientation for the OBS, this gets the filter to fit nicely and looks more professional.