bro lan d,
my fren have tried it on L2, using ZIP Decarbonizer... he got problem of black smoke (carbon) coming out of his exh tail and bad idling.. foremen sprayed if into throttle body (using spray can de-carb), and oso at vacuum hose (sucking one)..
black smoke gone... idling still the same. a week after, he sent back his car to change the engine's head (after i told him i got the same prob, and the prob was cracked head)... when the foremen dismantle the rocker cover (infront of us) surprisingly, inside it all clean.. no taik-taik minyak (u know what i mean)... and on to top of that, pistons were all cleaned...
it was very worth it for rm50 charges