[Kostamojen]

Just the air filter in the box? No.

 

[Kostamojen]

will adding the K&N filter void warranty?

No.

But don't expect any power gains. I've only run them on some of my cars just so I can clean them when needed rather than replace the whole thing.

 

[Kostamojen]

You mean change the ECU mapping in sport mode? That might be possible. Won't do much fore HP unless you've done other things to the motor though (intake/exhaust/etc.)

 

[Kostamojen]

Yes, this could be done. Subarus have a sytem on STI's called "SI-Drive" which has 3 settings, ECU programers have been changing the mapping on each setting with that car for awhile now. It shouldn't be much different with the CT.