As many have already mentioned, the M5 bolt on the seat post clamp is actually too long; it doesn't sit flush with the top tube, causing the dust cap to stick out. I’ve now bought a 30mm M5 bolt, and it fits perfectly. I’m using a Giant dust cap, and it fits perfectly now, too! I can provide feedback on the headset once my handlebar arrives. I’ve ordered the FSA No. 55 LS and a Lightest HBR17 cockpit with an FSA adapter. Still waiting for delivery!