while the sps did have 8 friction plates, it had a surflex sintered brass looking (or whatever it is) friction plate set, which also had thinner 1.5mm steel plates. i don't recall ever actually measuring the thickness of one, but from memory it's much the same as the organic 7 friction pack at 38.5mm.
the 1098, etc, pack has 8 frictions and is about 41mm thick from memory. they also have a lot of 1.5mm steels, but are still thicker than the old surflex 8 friction pack.
know all wanker