I have just found a leak on the LHS as well. I assumed it came from the welsh plug behind the exhaust manifold as there was some pinkish residue there. I pulled the manifold (again) and tightened the welsh plug by a 1/3 turn and cleaned away any pink residue - let's see if it fixes the problem. I had read somewhere of this happening recently - might be worth checking this too.
Cheers,
Franz

