VTR great car to strat with Light, good 8v engine

top stuff
Basically engine tuning is getting more air and fuel into the cyclinders burning it then getting rid of it as fast as you can.
Airfilters/Induction kits get your air in quicker
Your ECU will (to a point) adjust the fuel itself and put more in
Then a Performance Exhaust and/or Performance exhaust Manifold will get the Gases out quicker
There by increasing the engines performance.
Check out
www.kam-racing.com for good airfilters and manifolds then its just a choice of the exhaust which is more down to how you want it to look as most of the leading brands Magnex/Janspeed/Piper/Scorpion will perform pretty much the same give or take a pony or two
Dececnt airfilter - about £100
Decent Manifold - about £150-£300 depending on brand and type
Decent Exhaust - About £200-£300+ depending on brand and type