Hve to agree with PJ on that, upto about 380bhp you can get away with most yourself but over the 400bhp mark you got little room for error, spec if you havnt done that sort of thing before. Plus you would have to have 100% faith in the machine shop your using as within reason most should know what their doing but trust they dont!!! As some ppl have found out on here with no names mentioned even 'supposed' tuning companys have fucked up royally when it came to building a high bhp engine, and if it doenst die when in their hands you could end up footing the bill.

Plus theres the fact of what U want out of the engine?!?! Using an RS500 set up you can get 450-500 easy which uses standard pistons etc just needs the right manifolds T4 and mapping etc, where as a low comp 450bhp rebuild has alot of variables, you could use a t4 for balls out power or a t34 for drivability but wont have the top end pull the t4 does. Then for cams again comes into how u want it, bd10s 14s etc etc.

So to ask what parts u need is a bit schetchy without knowing how you want it