Not that I know of. "Variable resonance" manifolds aren't new. I used to have a 1994 Ford Probe GT (with a Mazda 2.5L V6) that had something similar in its intake. They even touted it as "VRIS" - variable resonance intake system" - or some such:
That system actually used butterlies to optimize both runner length and intake frequency to maximize torque.
I've not seen anything like that for the 2V though. It could be partly due to the fact that the stock 2V has a relatively low redline and thus may not really benefit that much from shorter runners. There are short-runner-only manifolds out there like Reichard racing's:
but they're really designed for engines that can spin into 4V territory and which have cams and heads to match.
It'd be neat to see if there'd be any benefit to making such a manifold for the 2V. I doubt such a venture would be cheap though.