so i read some threads about this but this seems really shotty.

first is the OEM filter, with its air deflector things and all.

this is the underside of the OEM, notice the groove it has to fit tightly against the airbox.

and this is the K&N filter, the top looks like the bottom, no groove nothing.
will this stay in place? the air is flowing from the bottom and the top of the airbox has nothing to hold this into place.
did i do something wrong? it doesn't seem that i can use the old air filter holder to put the K&N one in.

 

I feel like i had the same problem but it turns out i had installed mine upside down. I just flippped it over and it worked. but it will fit :P

 

sooo, after some digging i've seen that some filters come with sealing grease, this however did not.
honestly i don't like the chance of grease being sucked into my intake, because again, it doesnt get held down by anything.
can't find any installation instructions out there for this filter.

 

You've got the right one. As long as you have it in there with the "this side up" facing up it's fine. I've got the exact same filter and have been running it for years w/o any problems.

 

seems to be allright, if anyone stumbles in here looking for gains, it does seem that i've lowered 50mph by 200rpm, can't say for any higher speeds, with this rather than my dirty OEM filter pictured.

 

WTH are you talking about? RPM at 50mph is a set mathmatical point based on gear ratio. If your rpm at 50mph is different now then its because your clutch was slipping and isen't anymore, no other way to make it change.
As for the filter, theres nowhere for it to go inside the airbox so you don't have to worry about it not fitting like the oem. I bought one then decided againts using it as it doesn't have the airflow control flaps like oem and I don't want to hurt low rpm efficiancy plus it doesn't actually gain you any power at all on an F4i.