I'm pretty sure that the coasters with the most inversions is Dragon Khan in Spain with 8. There is also a coaster down in Brazil that I think has 8 inversions but it could have 7. In the USA I would have to say Kumba and Montu each with seven.
Kumba: loop, diving loop, barrel roll, cobra roll (2), and 2 corkscrews.
Montu: loop, immelian (sp.), in-line twist, batwing (2), loop, and corkscrew.
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Parks for 2000: SFEG,IOA,MGM,WDW,PGA,SFMW,SCBB,Lakeside.