Get a sports cat manifold.
Get an exhaust
Get a lightened fly wheel
Get a crank out of a 1600
Get an induction kit
Get a live map
Get a turbo
Get a supercharger
Get stripping out the cars weight
cams you can get reporfiled with Kent or Piper i think for abour £250-300
Sports cat is about £300 from regal, not sure about that
Crank you get from an engine, off a scrappy, probably have to buy the whole engine though.
ITB kit of MarkyG
Exhaust off ebay
Live map off regal
You would want fast road cams, they would re-profile your old ones so your car would be off the road for a while.
I'm sure somebody would do a sports cat....i might be wrong with that one though. You could always get a new exhaust manifold then put a cat further down, would have to re-wire the O2 sensors but shouldn't be terrible....unless i'm missing something.