Thanks for the post. I replaced my plugs recently and saw deposits in the chambers below them. Was surprised to see the amount of carbon as my engine has less than 40K miles with an oil catch can always in place since delivery, on stock boost mostly. Doing this at the same interval as plugs seems sound.
Shops here charge an amount that would cover the investment for the tools required for this job, if not more. Once unsure about the DIY, not anymore
