I had my MINI in to replace the PCV hose (small rubber hose at the back of the intercooler that rots/collapses and makes a mooooing noise on deceleration) a couple of weeks ago and was told by my dealer that because I have a K&N Typhoon the warranty should be void but he would make the repair just this once.

I was worried about this as I fitted the K&N because of a personal dislike for plastic airboxes and panel filters that goes back 10 years of motoring and because I like the noise, any power increase was really beside the point for me (wow 3HP more :rolleyes: )

I would argue that fitting a better quality aftermarket item should actually reduce the number of warranty claims (my panel filter was damaged when I got the car but opted for replacing it myself). I have kept my original airbox and torn filter and will put them back on for services if this becomes a recurring issue with my dealer