So i looked around last night on here for a few hours. I could not find a straight answer on the balance of the I5. Are they internally balanced, or externally. There seemed to be some debate on this. The crank pulley tool nub made some people say external. I think they are internally balanced motors. I have this question because i just installed a custom flywheel on my 85 4k and now have some vibration. I really would like to settle this matter. I am going to be building a stroker soon just want to add to my audi knowledge.