I've just had the glow plugs on my 306 changed and on picking it up have noticed that it a lot more smoke is being discharged from the exhaust, especially at >2500rpm. The garage had to remove the manifold in order to change the plugs. I assume that they did something wrong when replacing it. Can anyone suggest a possible cause of the problem? Syptoms are excess smoke from the exhaust at >2500 rpm and accelerating to a speed above 60 is proving very hard too. Thanks in advance, Dan.