The the gap between body and chassis is too big. You need to cut this wall. Swap the front/back racks of GF-01 Done the wall cutting. The battery lid will become obstacle of Willy's feet. Cut the white line part. And this white line area. 3 holes lower. You need to use short battery. Also use low height servo. Compare with WR-02(right side). The GF-01 with smaller gap and sexy waist makes it sporty. Painting. Change WR-02 tires (4 rear tires.) and the job is done.