Shrug, smirk, and quiet arrogance because Kazu wasn't quite sure verbal would work. He'd always be proud of his ATs, but that was required- even if he wasn't the best (or close to it), he was relatively sure he could beat a pair of boots. Well, he hoped so. It'd be a bit weird not to, right?
Sensing those creeping 'average' thoughts getting in, Kazu focused on talking. "Go for it. Or do you have to warm up?" There was an edge to his words, that even though they were competitive, he didn't quite mean them-- an edge placed there just in case. Never knew what the mafia was going to take seriously or not, anyway. He hoped Gamma'd agree to just racing; he was a speed rider, and showing off was too much like fooling around, only with more pressure and expectation.