Not an LS2..
As for fuel economy, the controller is just mimicking what would happen if you were heavier on the throttle pedal without you having to actually be heavier on the throttle pedal.
Your WM2 should have an L77 engine fitted.
A throttle controller makes you want to be a leadfoot, wont help economy at all.
I have one fitted to an LS3 to try it out, but I wouldn't recommend it, as I think it was a waste of money.