What did I do wrong? FIXED IT!!

did the convertor have ANY fluid in it when you replaced it? I doubt it was empty as they cant dump out 100% due to their design. I believe the max fluid capacity with a empty convertor is 9 quarts ~ 8.5L. A whistle could mean pump aeration (doubtful if you got 10L in there) or a clutch pack pressure issue. I put 5 qts in a C4 once and 2 ended up on the floor, bubbled right out of the vent hole, oops!