Xcessive Manufacturing 4 Injector REW Lower Intake Manifold -Cast Aluminum 4 Injector Lower Intake Manifold -Designed for top feed Injectors From Xcessive Manufacturing: Xcessive’s all new cast aluminum lower intake for the13B-REW engine can utilize the stock side feed fuel rail, aftermarket top feed rail for 2 injectors or up to 4 top feed injectors with four place rail. If your planning on upgrading your primary and secondary injectors, do it with a single rail and simplify your fuel system at the same time.   Using shell cores for a quality surface finish when casting the intake runners, we achieve 20% more flow than a stock manifold, this manifold can be bolted on and perform better than a ported stock manifold. We’ve also managed to get the front to rear secondary ports to have matched flow rates, which is nearly impossible on a stock manifold, this ballanced flow is especially important in higher boost where it matters most.   Because this is a new casting, there is no thinning of the port walls from extrude honing or hand porting to obtain high flow rates. This also means there is still room for an all out race port never before attainable with the stock piece and at 12% lighter than stock. With removed heat riser passages and smoothed exterior, this piece has less opportunity for heat soak and much cleaner look.   This manifold is designed to use standard rubber o-ring injector installation. Metal spacers/adapters may not fit due to some modification of the injector port size. Expect to re-tune your motor after installing the manifold, the increase in flow rates can change the air fuel ratios.