I never noticed before , but I see pictures of the Coombs MK2 , and the Exhaust tail pipes are more to the centre !
Found a list of Coombs modifications and it says —
Exhaust system - supply and fit Servais silencers but retain standard tail pipes ; cost £11.110d
As above but with Modified tail pipes of the straight through pattern : cost £21 0s 0d
As far as I know the tail pipes are after the Silencers,and are straight through anyway as in air flow , looking at where the tail pipes exit the Coombs , I would say the pipes are straight from the back boxes
Did Coombs add a extra £10 for 2 straight bits of pipe ?