Yamashita, who shares the #14 Rookie Racing Toyota with Kazuya Oshima, made the remarks in the wake of this month's penultimate round of the season at Autopolis after battling the Impul Nissan Z for fourth place.
Although the Impul car shared by Kazuki Hiramine and Bertrand Baguette was running with a fuel flow restrictor, Yamashita was only barely able to hang on to his position after Hiramine made an error and ran off-track in the closing stages.
