well tuning one of these is expensive business,in my mind there is two ways you can do it nr1 NA power,nr2 FI and very early in the project you have to decide which way to choose ,that way you will save your self some money for sure.

Also way before any tuning you should do these things to your engine, a)cylinder head gasket(weak spot on these), b)rod bolts, c)vanos and mainly vanos pump drive, d) cam bolts.

Nr1 NA power option,-again depends what you want really-if you dont want to spend mega money there is one nice option K&N cold air system(300-350eu),alu flywheel and clutch(650-850),and remap (350-500) after these simple mods car i did was really transformed was so much sharper more aggressive and the owner was really happy with the results,actually we didn't rolling road it,but the butt dyno showed some healthy gains.

more expensive NA option to follow will update this post later......