[beef_bourito]

the reasonpeople do twin turbos is simplicity. instead of having to route both exhaust manifolds to one turbo with equal lengths so that you have the same backpressure on both sides (ony in a v engine) you can just have one turbo per manifold. with long inline engines (6 or more) twin turbos are sometimes used because running 6 or 8 tubes into one turbo can be dificult and take up alot of room (if you want the same length tubes from each cylender). the intake setup would be pretty easy, just have a y pipe running into one throttle body (or you can have two throttle bodies that run into a y but then you need two throttle cables and such) and then run it into the intake manifold. also to make around 400hp on 20 psi would take some stronger internals, get some forged pistons, con rods, crankshaft, balance the engine, lower compression, get a camshaft better suited for turbo application.