Interested in your "klacking" noise, I get that on speed bumps but havent identified where its coming from.
Where was the oil leak? I have oil at the base of the chrome pushrod cover... Dealer said its probably coming from the oil breather which is somewhere behind the air filter. I dont see any trace of oil from further up, but havent taken the air cleaner off to check.
Are you sure the left exhaust is louder? Not just closer to your ear, as you are left hand drive like me I presume?