yeah what everyone else said. headset and stem.
king headsets are nice alright...if you've got a) the money and b) the patience to put up with the finickiness of it. they also creak like mad on a BMX because they require the head tube to be faced PERFECTLY, and most shops don't care enough about a BMX bike to do it right, or they just don't know enough to face the headtube. king headsets are the hardest to set up properly. also king headsets aren't really that great for BMX, especially if you're planning on abusing the bike...i'd rather get a $20-$45 FSA or primo, or dia-comp headset than drop $100 on a king, only to have the cups crack a little down the road...