Perhaps you're thinking of the astonishing Oracle-sponsored Turbo Raven which had a 750 shp PT6 engine and could climb to 10000 ft in little more than a minute. It later climbed to around 20000ft in just over 3 minutes.... It had a thrust to weight ratio of about 1.5:1, could climb vertically and then hover in the climb. It could also use beta reverse thrust in the air and its airshow routine used to include a steep descent using this feature...
Sadly it was lost at an airshow in 1999; fortunately the pilot, Wayne Handley, survived. He said that the engine didn't spool up when he took it out of reverse pitch to fly out of the steep descent manouevre. However, post crash strip down showed that the prop had been in the normal forward flight pitch range and that the engine had been in the mid to high power range at impact. The NTSB concluded that he hadn't maintained sufficient airspeed and had simply stalled......
See
http://www.ntsb.gov/NTSB/brief2.asp?...00LA003&akey=1