if its a post 90 mk2 (hazard on steering column) its dead easy as all the engine loom will plug straight into the fusebox. If its an early one then splicing is required!
audi100Quattro is correct, the MK3 16v uses digifant managment. Its an upgrade from the MK2 2.0 digi system, which includes 2 knock sensors, a lambda sensor and a crank sensor, amongst other things. Also it has no MAF or MAP sensors.