A friend has a 2 seat Grumman with a 180hp lycoming on the front (ken blackman has STCs for cheap) and it is most certainly not the Grumman being spoken of here. 1800fpm with the two of us on a 75*, 65% humid day, 175kts gps (about 160 indicated) ground speed at 9k feet @ 9gph.
Seen it with my own eyes as I was there when it happened.
The only thing I didn't like was high approach speeds with those short wings.
