That's cool. Your post made it seem to me that you had experience with installation ........ just looking for some pointers. I clean my air filter with every oil change. Why? .......... because I can, but that's just me.
It looks way easier to get to the filter for cleaning for one thing. The Gruppem looks like you have to take the box apart more than halfway to get to it. The Gruppem also has its own intake duct that fits down in front of the radiator. You have to undo part of the top of the front bumper to get...
I also have the Apexi and you have described it perfectly. It also has valve control for those that want it. If you sense some cabin drone, just barely feather the accelerator and be amazed ......... ;-)