As most here realize , DI engines form intake deposits which traditional gas tank additives can not touch . Therefore , I was curious about newer products such as : 3M's intake cleaning kit or BG's intake cleaning kits for the home DIY upper intake cleaning project ...Do they work ? How effective are they ? * Hyundai wants close to $300 to do a recommended upper intake cleaning service every 30,000 miles - there has to be a less expensive way to maintain a DI engine from forming upper intake deposits !! Your experiences and opinions are appreciated ...