SURF150

It looks like someone/the previous owner added either an additional (guessing height) 3/8" plate above your rear block for a tiny lift, or maybe it was added as a shim to alleviate a possible shudder or shimmy vibration that was felt after raising the front with leveling spacers. This is just a guess on my part as to why that "shim" looking plate is there; it shouldn't be. Is the shim tapered fat-to-thin, or is it the same height all the way across? Either way, you can and probably should have it removed if/when you replace it and use only a single block for height. I'd say if you went with a rear block somewhere between 2-2.5", you'd be satisfied. Again, remove the current rear block and that shim thingy altogether if you do.