Can anybody tell me the likely / possible dangers from having a complete new engine fitted into an Impreza turbo (garaged fitted - car is a MY94)? Am I letting myself in for a whole host of potential problems or if fitted properly should it be ok?

Cheers

 

If the engine is built properly and competently fitted, there's no reason to think why there should be any undue problems. Changing the engine is a pretty simple job, no excuses for getting it wrong.