EXT43 has a special active foaming agents which will cause EXT43 to evenly coat the interior parts of the combustion chamber and intake manifold (see illustrations). EXT43 active cleaning agents will affectively eat away at carbon build-up, varnish, and other deposits that affect engine operations. Fuel additives (applied into fuel tank) typically cleans a very small area between injection nozzle and combustion area. EXT 43 cleans and penetrates all areas between throttle valve and combustion chamber. Results are IMMEDIATE!