it would work out cheaper to build your owne engine than buy a focus rs one, they tend to go for around 1200 for just the engine and you can buy a set of forged rods and pistions for 800 and get valve springs for 200 and spend some money on cams if you wanted to (say 400 for cams) and you have a engine thats stronger than a rs one and a better spec, or keep the standard cams(good for 300bhp) and have some head work done, you can use ofab managment on it and get a t3 on a escort manifold or get a focus rs one(more money but fit better and you can buy off the shelf bits for the exhaust to fit)