Very simple, fits well, and breathe's excellent. I chose to use the AFE big boost filter, it's a very large nice filter and I love having the pre filter in combination with it.

The filter was very easy to install. I had to modify the battery box or the filter would not sit under the hood. (The back side of the battery box would hit the filter and the filter would sit too high) Made a nice difference in sound, I can hear it's breathing much better.

I got the AFE Big Boost filter instead of the normal 6637. Before that the truck which is a late 99 SD had a K&N OEM replacement filter in the factory box. Right off the bat I see quicker throttle response, and a huge sound difference I love it. the truck already has TS tunes, banks trans commander, and banks monster exhaust on 35's. This intake brought my truck to a hole new level of life. Didn't require any cutting the box just take everything apart and it fits nice and snug. Also I highly recommend the Pre-filter. Haven't noticed any real MPG gains or any significant EGT difference but I'm still hammering down because I love the sound.

This was a quick and easy upgrade to my Truck.

Easy install. Had the 6637 on my 97 OBS. As a stand alone mod, the truck most likely breathes easier. Don't have any solid numbers regarding mpg increase or gains in hp or torque. But I installed it with the FRx, a compressor wheel, CVD's, and banjo bolts and the truck does feel less laggy and I notice a smooth and constant power delivery. Waiting on the exhaust to arrive to truly unlock all of the magic!! The 6637 is a solid supporting mod, much better than the stock air box.

My wife and I have a '99 F350 crew cab dually. It was obviously being choked to death by the oem dirty filter. We replaced the filter with the 6637 kit and wow! Throttle is more responsive and our gas mileage has increased by about 50 miles. Great product and service.

Installed a 6637 kit on a 2001 F250 PSD, four wheel drive with the ZF 6 speed. This is the first performance mod to the engine. Installation was simple if you follow the directions. Unfortunately, I have not seen any improvement in fuel mileage or lowering of EGT's. The only "turbo whistle" I'm getting is at wide open throttle and it is very minimal. Seat of the pants acceleration is hard to judge, but I do see a slight improvement there, all be it very minor. I'm hopeful the improvements will come after a turbo back exhaust is installed.

I wish I would have found this filter set up a long time ago. The pre-cleaner is a great old school idea. I felt the engine running smoother, with faster turbo spool-up, smoother shifting and all around better acceleration. AMAZING. Thanks to P.P.S. (performance power stroke) in Huffman, Texas for turning me on to this filter. However, The directions need some help. They fail to tell you that the battery-box / air cleaner-box must be cut out almost entirely only leaving enough to hold the battery in place. You really need to remove the battery to do all the cutting you need to do also. Late 99 f250 4x4 4door 240k

My factory cover was broken and I needed to replace it. The 6637 kit works great with my stock engine. I didn't notice any quicker spool up and mpg's are the same. I can hear the compressor wheel hiss when pulling a trailer. I am satisfied with the setup and it is the first step for making other performance mods to the engine.