Compare stock exhaust manifold (2½") to new 3½" on the left.

Compare engine to turbos manifold, Jap on top, ported USA on the bottom.

Japanese exhaust manifolds with turbos

Japanese exhaust manifolds with turbos

USA exhaust manifolds with turbos

USA exhaust manifolds with turbos

USA turbos/manifolds on left, Japanese on right

Compare engine side of turbo manifold, Jap on top, ported USA on the bottom

Compare turbos, Japanese on left, USA on right. Note that although USA is smaller it does flow more air due to better A/R ratio and a larger scroll area.

And just to see if you're paying attention, here's Lindsay and his Supra going down the world's steepest street in Dunedin, New Zealand.