Zayed,
Thanks, I may run a spacer too just in case the tips are too much heat for the bumper!

Sulaco,
Thanks for the info, I think I will keep the C43 cooler the way it is and plug up the holes on the CLK55 radiator, the C43 radiator I have has finer fins but they have been damaged by another owner whilst removing the viscous at some stage so would be nice to change it out.