Full Exhaust System Is it Worth it?

[simonr]

I have been to two places to get an idea on getting an exhaust system.
First place Lambros Hitech Mufflers in Darlinghurst,
i spoke to Lambros himself and he said that he could custom make the header/extractors and all up would be like under 2grand..
He mentioned he had done Marcus's from infocusmotorsport and some others from Herrod Motorsport..
Next i went to the local place in Bathurst. they couldn't get extractors either (as expected) but they also said that their is no point getting a new cat and they said they would just put a 2inch cat back system for 300 bucks + the new tip..
Anyway is it worth spending all that money for a few HPs? will it all be benefital once i get the intake and throttle body in there?
If i get extractors with the stock cat will that be useless?

Im just after a lil bit more performance and obviously the sporty tone..

I wanna break the 100kw mark!! and possibly keep up with the gti golfs and peugeots n St170s :P