Idk if it’s placebo but my exhaust noise seems a lot lower and the engine feels smother. Anyone else have any experience with gumout?

 

It is more than likely placebo. With Top Tier fuel, you would get essentially the same type of cleaning on a regular basis. Having said that, from reading Gumout's web page on the product, it does claim to be able to prevent buildup and reduce friction. I am pretty curious.

Personally I don't plan to use anything like this in favor of simply using Top Tier fuel.

Maybe try checking out ChrisFix?

From having watched this video, it seems like the best strategy for dealing with carbon buildup inside the combustion chamber is prevention. So, using fuel additives early and often so that the "sludge" (as he refers to it) does not have time to crystallize. Once it has hardened, it seems it's much more difficult to remove.

 

Yeah I have pretty much been trying to prevent the buildup been using 94 gas plus this gumout not sure if it’s necessary cuz the car is about 60k km but hey better safe than sorry.

 

I use Techron Concentrate Plus Complete Fuel Cleaner every 3 months, it's put in every 6 months by the dealership (Hawaii maintenance) anyway and it's cheap at Walmart. I believe this is the same stuff relabeled as Lexus Fuel Cleaner but I may be wrong. I don't notice much except maybe a few more miles on a full tank and easier to get those pops.