i have a 1600 with an fj20 in it as well as my 1200 sedan. when i park em next to each other you can see the size difference in the two engine bays. the fj is a HUGE engine, mine was from a dr30 skyline so it has the bigger intake plenium and i think bigger exhaust manifold for better power but the s12 silvia had smaller manifolds witch may suit a 1200 engine bay. i love the fj, it dosn't have the same sound or feel as other 4cyl turbo engines, its chunkier and feels more brutal under power especialy when the boost is wound up form 8psi to 15