The guy I take my bus to uses Auto Care Centre in Morley - 0113 238 3500. Mine's only been lowered by about 3 - 4 inches, but they seem ok with that (although it did fail its test today [DISAPPOINTED FACE]).
Herbie Hospital are good chaps and know their stuff.
I got my bus MOTd at a local garage near the airport just fine, mind. Needed a little bit of babysitting but they were good.