I would like to start by saying that I have enjoyed reading everyone's posts; they've been quite inspirational after my disappointing experience with the NQD Hydro. I Just bought one recently and was disappointed with the snail-like performance. I previously bought another e-bay special - the EP Wing Speed and had much better results. Only thing is, it disintegrates and sinks upon impact - Big OOPS!. Hence, here is my take on modifying the NQD Hydro:

2x Cordite SS1 700 Series 1/3HP electric motors
2x 7.2V battery packs
2x 30A relays

I plan to mount the motors in the original spaces using the existing drivetrain
The output from the existing esc will be used as the signal voltage to actuate the relays
Battery packs will be in series, esc will be paralleled into one of the packs
Motor negatives will be paralleled to battery negative
Motor positives receive power from the positive outputs of the relays

In a nutshell, what I'm trying to achieve is to increase the motor size and battery size while preserving the original vector push design without burning out the stock esc. I like the vector push because no additional equipment is required for steering. Setup should cost just under $150 (The motors are the biggest cost at $65 a pop). Need all comments and suggestions. Thanks!