What'll be your test equipment?

My M18 with a 9000Kv motor.

On 2s?

Yes. Well actually 2S2P.

I just looked at the instructions again and it's 30A (50A burst) and 4S capable. The BEC only handles 3S though and you have to disable it for 4S.

Seems like it'd be hard to find room for a BEC on a car that will use a 30a esc.

Some BECs are small, but you really don't need to go above 3S in the little guys.

Yeah, I ran an 18t on 6s before though. I can't even remember what esc I had. I was running a hacker e-37 with 6s thunderpower lipos.

I was actually talking about 3S with a 9000Kv+ motors.

Linear BECs on 3s are ok as long as the current draw isn't high. In something that small, I can't imagine the servo drawing any more than 0.5A bursts at most. At 3s and 0.5A, that's only 2.5w wasted...