Recently scheduled a carbon cleaning and my shop recommended to proactively replace the injectors as they tend to get gummed up as well with age. I'm certainly glad that I did; the tech took photos of the ones that came out and yeah they were pretty bad. That's with running good gas (Shell 93 V-Power) and good oil 100% of the time I've owned the car. As for the injectors and my UroTuning experience, it's been excellent! The product arrived on schedule and in perfect condition. A few stickers in the box are always awesome too. In summary, if you're doing a scheduled intake valve carbon cleaning service I'd certainly recommend ordering a set of these to do as well "while you're in there". My shop didn't even charge extra to drop them in. UroTuning is the best! I look forward to doing more business with them in the future.