I know a 55 with two 550's on it. Was getting a TAS of 210kts. Infact it was so fast, the engineers reckon the 550's were responisble for all the fuel that started to leak out beneath the wing!
That would be the bladder tanks which dry out and crack then leak after a couple of years if you leave the aircraft stored often without full tanks
Any Bonanza/Baron owner knows the pain
