man up and run the larger turbo, make sure you sure use a low mount manifold. heat coat the turbo, leave the stock heat shield on (if any?).
another words, do it and hide it. if the engine bay looks like a race car, you ll get pwned, if it looks stock you should be fine.
i saw a cop checking over a friends skyline, even looked at the turbo, completely missed it was a HKS turbo.
in summary, basically every mod is illegal these days.