Hi, In my old rs2k I had
Superchip - £100
Fast road cams - £150
Blanked off egr manifold and heat wrapped.
Remove the exhaust manifold and remove inner welds then weld outer welds on it.
De cat, I had a J reg so it was legal.
Janspeed exhaust.
You can go down the turbo route but you will need a mega squirt ecu, cosworth fuel pump, calibra turbo pistons, s14 injectors, s14 exhaust manifold and turbo.
You can get away with standard rods as long as you don't go mad with loads of power and high revs.
If you get rods then I have seen an rs2k turbo with 300bhp. The rods are not cheap!
If you go down he 45 route with megasquirt I've seen 240bhp
Join rs2000-16v.co.uk they have a 2.3 guide. More torque and around 170/180bhp
I wanted to go down the turbo route but ended up breaking the car up due to rot.