Magnum's nowhere near the last hyper Arrow made. Steel Phantom, Desperado, and Blackpool's Big One were all built after '89.
As for Morgan, they've got a few hypers under their belt, too. Besides SD2K and Steel Force, they built two other 200+ footers for Cedar Fair, Valleyfair's Wild Thing and Worlds of Fun's Mamba. Also, they built a "junior hypercoaster" for Sea World Texas called Steel Eel, which stands at 150' tall.
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Matt Lynch
Co-Webmaster, Kennywood Boulevard
http://kennywood.coasterbuzz.com