I just had a brand spankin new Cobb RMM installed 2/2/16. Extremely happy and it should be among the first mods imho.
As far as NVH, the engine is slightly louder while driving, pleasantly so. Slight vibration at idle and you wouldn't notice it if you didn't look for it. Idling with A/C sounds faintly like a 32ft organ pipe. Think of the beginning of "2001 A Space Odyssey," only verrry faint. Not a bad tradeoff and I definitely would not switch it back to stock.