Berryman B-12 Chemtool Fuel System Cleaner (part #0116) is very effective at combustion chamber cleaning if want to perform a cylinder soak. That is accomplished by pulling the plugs, putting 0116 in each cylinder, letting the product dissolve the carbon, and then removing the mixture from each cylinder. If you have a V-configured motor, then it may take nearly a full bottle of 0116 per cylinder to ensure that you cover the entire compression ring, especially if that ring is stuck and allows some of the B-12 Chemtool to migrate toward or into the crankcase. However, if you don’t mind soaking one side at a time, you may be able to jack up one side of the vehicle to flatten that bank of cylinders and thereby cut the amount of product required. You can also buy Berryman B-12 Chemtool Fuel System Cleaner in a 1-gallon size. That part number is 0101. Alternatively, 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. That particular product is also available as “Step 2” in our Professional 3-Step Fuel System Maintenance Kit (part #2630).