doesn't make sense to me remove the last cog when you could simply set it up normal and the last click would probably stop right at the 2nd to last cog anyways. At any rate, your probably better off just buying a new 8 speed casette and then I don't see any reason why it shouldn't perform fine for you. RD's are pretty much interchangeable, I don't know how different 8 and 9 speed casette spacing is but putting on an actual 8spd casette could only help matters. I'd probably put a new chain on at the same time the two combined would probably be about $50. It's far cheaper to do this than to get a 9speed shifter.