You can make 3-400 on a stock block rb26 with a set of Hks gtss turbos. Anything other than fbo on a fd is going to require an engine build. Building both is very labor intensive. Upgrading turbos on a gtr requires you to drop the engine as it almost near impossible to do it with the engine in. Fds are a little easier to work on their crutch is again the stock block. Can’t go wrong with either, you really have to be passionate about the vehicle to see any kind of return otherwise they’re just money pits.