All three products are capable of combustion chamber cleaning but use different methods to accomplish it. If you just want to clean carbon buildup off the pistons and rings, especially if the rings are sticking, then Berryman B-12 Chemtool Fuel System Cleaner (part #0116) will do so by way of a piston soak. However, that is accomplished not via the vacuum system but rather by pulling the spark plugs, putting 0116 in each cylinder, letting the product dissolve the carbon, and then removing the mixture from each cylinder. You can also buy this product in a 1-gallon size (part #0101). B-12 Chemtool Total Fuel System Cleanup (part #2616) is a great, high-performance fuel additive for someone who just wants to put something in their gas tank the next time they fill up. It will clean the entire fuel system, including fuel injectors, carburetors, intake valves, and combustion chambers. Again, though, it does not make use of engine manifold vacuum and does not have the right detergents for such a method. Instead, Berryman B-12 Chemtool Total Combustion Cleaning Kit (part #2610) contains high-performance detergents specifically designed to thoroughly clean intake valves and combustion chambers by way of vacuum induction via either the PVC valve or the brake booster. If you specifically want to make use of the manifold vacuum system, 2610 is the best cleaner for the application. Please note that the 2610 chemistry is also available as “Step 2” in our Professional 3-Step Fuel System Maintenance Kit (part #2630).