Found an error in the kit, actually a guy on an other forum noticed it
... As you notice on the boxart, the fuelfiller is on the bonnet... On the real clubsport porsches, the fuelfiller is located on the front weel arch, just in front of the a-pillar... I'm going to leave it as it is... It's no problem to sand the old fuelfiller out, but scraping out a new perfect simmetrical filler on the wheel arch is a bit hard