he said "all the carbon buildup" and a lot of that is just a byproduct of direct injection. and depending on the setup you're possibly still getting oil in the intake. I put an intercooler and catch can on a friend's car with a BL plate, checked it after a month and still found the usual puddle of oil in the inlet. hence some people still getting white smoke with just a can.I disagree that cc do nothing. On the street, I'd agree, but I catch oil in my cc on track and at autocrosses, which would have ended up inceasing buildup.