opinions vary mate but the shorter primarys on the 4x4 manifold increase spool up time of the turbo, and i have seen with my own eyes 380bhp+ cars with 4x4 manifolds on.
the 2wd manifold is more popular tho for some reason even in lower powered cars, i myself run the 4x4 manifold as they dont tend to pull exhaust studs out and dont need a damper unless your running a huuuuge turbo lol!