Not really worth the hassle mate, keep it standard with a descent exhaust, filter and etc. I think you should be hitting around the 230bhp with just a couple of simple mods, 300bhp is about max without changing the inlet/plenum as they are restricted. Install a set of bob cam and a set of Vauxhall injectors. I think the boa is a better plant slight down side to boa around the cranks and the bob block will be stronger.