These diagonals as they are called are nearly all 1:1, that is, no magnification. They are only used to turn the image right way up, and give you a comfortable view from the side.
If you want a bit more magnification you can either get eyepieces with a shorter focal length, eg 15mm or 10mm
http://www.optcorp.com/product.aspx?pid=724-2247&kw=&st=0 or magnifying Barlow lenses, which go in between your KE20 and the scope.
http://www.optcorp.com/product.aspx?pid=115-1751&kw=&st=0 I would recommend one or two more eyepieces. Bear in mind that there is a limit to magnification your scope will support before the image goes all fuzzy. Your current EP gives 550/20 = x27 magnification. To get x100 you would need an EP about 5mm. This will be about as much as your telescope will support.
So I'd buy 2 more EPs, one about 5-6mm, and one about 10-12mm.
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