[icfish]

Anyone have this done or have their dealer recommend it? Just BS or something worth doing. $400.

 

[sevenslot]

I have not done this nor had my dealer recommend it. It really depends on what they're cleaning carbon build up off of/ out of. Frankly, should be covered under the extended emissions warranty but different topic.

If they're suggesting the diffuser, I'd say do it yourself:

Same thing with the MAF sensor on the back of the engine. pretty easy to get to and gets clogged up with carbon as well