The bungs should really be left in as they are part of the road noise deadening. One could argue that with a roadster it'll make no difference 
Secondly do remember that because the drain plugs at the bottom are clear it does NOT mean the drains are clear. You really need to run a little water on the roof to see that it drains freely out the bottom. Any blockage is as likely to be higher up the pipe or just below the hydraulic motor.
Secondly do remember that because the drain plugs at the bottom are clear it does NOT mean the drains are clear. You really need to run a little water on the roof to see that it drains freely out the bottom. Any blockage is as likely to be higher up the pipe or just below the hydraulic motor.