Considering that the Skyline R34 GTR is one of the all time favorites of forza fans, it is a shame that there are so few customisation options for it. Other people have asked for aftermarket parts, as well as nismo parts, which would all be more than welcome. But something that would be much easier to implement and basically already exists in the game, in a sense, would be the raised version of the OEM rear wing. In real life, this mostly happens with some aftermarket risers but honestly it would be the simplest of things to implement in the original rear wing model. I attach an image of what that looks like. Usually, this upgrade comes hand in hand with the Nissan badge removal from the rear end of the R34 but maybe that’s something for another day.