I removed all the spark plugs and the front three had there gap reduced. The middle and right one (facing the engine) were completely smashed against the electrode. The left one had a gap of .032. The back three were gaped around .060. What is the correct gap, because I cant find it in the manual? There is also a mild knocking sound that comes and goes. It mostly shows up when the engine is reving down (in neutral). I haven't drove it yet so I dont know if there is any lose of power, but the exhaust used to sound fairly smooth now it kind of bounces occationally.