When I bought my '15 used from the original owner in the Summer of 2019, my car had had all of its modifications done at RD Engineering. FBO plus his "RDE800" turbos. The car was extremely well-sorted and drove beautifully. Ronnie was tough to get a hold of but when I did, it was easy to tell that he lived and breathed GT-R's. You'd be in good hands there, I think.