I put the AFE Stage II Proguard 7, got the slip-on pre-filter sock and a maintenance kit too. All from DPP.
Problems: top of filter just kisses the hood insulation, so I trimmed the insulation. And they sent the wrong color sock (wanted KY Blue, got some ugly yellow thing that looks awful when it gets oily).
Positives: well-designed, well engineered, easy install. Makes a great whoosh if you stand on it after each shift.
I would do it again, no question.