The Hasegawa 109 G-6 to K-4 series have completely retooled fuselage moulding cf. their F & early G series - the side cowlings are an integral part of the fuselage, with a solid upper surface on which to cement the seperate top cowlings.
The wings are from the earlier kitsets; the builder is supposed to inscribe additional panel lines to the upper, outer wings (shown on the instruction sheet).
One thing I have always done is to show the 'Boundry layer exit slot' on the upper, inner flaps (
http://109lair.hobbyvista.com/techref/systems/cooling/f_flaps.htm) This is easily done by cutting four peices of thin plasticard to the same shapes and sizes as parts B5 & B6 (F series kitsets) or F10 & F11(G&K). Cut 1 pair to be about 2mm short of the trailing edges, cement to the underside of the kit parts
(!don't use too much cement, which can end up melting or warping the kit components!) The other peices of plastcard can now be added, forming a sandwich - the boundry layer gap can be sealed at the sides with thin fillets of plasticard.
* * * * WARNING* * * *
*???* Careful reading of the 109lair description says that the 'Boundry layer exit slot was (quote) "...
discontinued with the introduction of the Gustav." *!!!!* Now that I look at photos of Gustav flaps - there was no boundry layer slot! AAAAAAAARRRRGGGGHHHHH!!! Don't bother modifying your 109Gs or Ks