if you dont mind getting your hands dirty you can service it yourself, awesome gti will take the piss on prices, just do an oil change and change oil, air and fuel filters, spark plugs. id do the cambelt too if you dont know when it was done. this will probably be a garage job

instead of an ecu for the fueling 16v's have a metal flap

so no chips im afraid unless you change the fuelling system.
id say the best value mod for good power would be the exhaust manifold (save loads of weight too, the originals cast iron) for a stainless one and get it setup at somewhere like stealth
