Fuel induction services are not a scam nor are they useless an offer no benefit. You take any direct fuel injected vehicle for instance and don’t do it and you will soon find out why the engine is loud as hell, poor fuel economy and performance and I have also seen pre detonation and engine failure. I have personally had to take intakes off cars and heads to clean the valves by hand because customer thought it was never needed and ended up costing thousands. Direct injection you no longer get the fuel passing over the intake valve to help clean it. So now deposit build up happens much sooner. At Hyundai we do it every 15k I’ve seen other manufacturers recommend every 10-12k. On mpfi and throttle body injection an the others where fuel passes over the back of the intake valve, yes they do stay cleaner an additives an good fuel help but still should be done every 30k. Look up how to do it yourself it’s homestly not that hard especially on a Honda 3.5. Then you will notice the improvement or use a scope through each spark plug before and after and watch the results.