I've just got a 2.5" press bent system with one muffler, the brand I've forgotten, paid $380 which included a 2.5" cat at Jack Beedhams redcliffe. It took a couple of months to fully burn in, but it wasnt driven everyday of the week, so if you're driving it more regularly it'll happen quicker.
I'm gonna wait a while before extractors, from what i've heard from alot of people is that fuel consumption will go up with them. Also I was speaking to a mechanic that used to work for ford designing the fuel injection systems and he told me it wasnt really worth converting over to multi-point.
Phat Drift Damaged
Cobalt Blue 1994 EF XR8 5 spd
Fully optioned - Sunroof, cruise, body kit
Stock as a Rock for the moment