yeah those chips are well bad.
bet option is start with the basics like Tophuh said. Get the engine breathing a bit better. you could take the cat off, but it's a pain putting it back on every year to pass the MOT.
a remap will work best after you've put these items on as the mapping will take that into account. you can also look at more lairy cams to gain some more bhp in the rev range.
short of that you're looking at expensive work being done like headwork and balancing parts. or a turbo bolted on
