Welcome mate, good choice. Use the 'search' feature above (when your in forum mode) to search for VTR tuning / power gain etc... lots and lots of info available.
In the meantime:
Enclosed Induction Kit (BMC / GREEN) = £180-£200
Full exhuast system s/s (Magnex / Custom) = £250 - £300
De-Cat (if not already done by exhaust) = £50-80
4-2-1 or 4-1 manifold = £180 - £300
And then ask the people who have gone beyond....
CAM(s) = £££'s
ECU REMAP / CHIP = £££'s
Go crazy ...
Turbo charger = £2000 - £4500
Super charger = £2000 - £????'s
Enjoy the site and your new toy.