trying to do some mod for my 550i. but got a question. Is that worth to spend couple hundreds $$ even $1000 to get a carbon fiber intake like Gruppe M ? How about the $60 K&N filter?

 

Save it... remove the charcoal filter instead...

http://forums.e60.net/index.php?showtopic=21796

 

Depends on why you want to do it. Performance wise it is never worth the money as the gains are minimal. However the SOUND is incredible on an intake and is still to this day one of my top 2 favorite mods ever. I love every second of driving my car so much more with the loud aggressive intake that just screams when you mash the pedal. It was worth every penny spent on it