Problem with exterior layer - a wave appears

hi, I am printing on Mendel90 and slice with slic3r with the settings:
layer_height = 0.2
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.2
; perimeter_speed = 60
; infill_speed = 80
; travel_speed = 130
; nozzle_diameter = 0.4
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.67mm
; infill extrusion width = 0.67mm
; solid infill extrusion width = 0.67mm
; top infill extrusion width = 0.67mm
; support material extrusion width = 0.67mm
; first layer extrusion width = 0.70mm

I printed this with support and I am pleased with the result, beside the wave on the face of the model. What could be the problem? The back of the model is really nice, but the whole front is kind of messy...and the top of the head.
I cannot realise if this is a problem from the print or the slicer.

Does those waves appear when pre-visualizing the gcode (say, with repetier host for instance) ?

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

I just viewed the G-code in Repetier and there are no waves.
Yesterday I printed the Nophead calibration object and it came out great:

How could I improve the top layers?