I have owned multiple Fiat's models and 850's (1 sedan and 3 coupes), but never a 600. I know the 600 is smaller and older technology (smaller engine, etc) for the most part than the 850. I noticed a few people have one of each and appreciate both. I have read that the engine in the 600 rotates different than the 850, so you can't just drop a 903cc into a 600 without changing rotation. It seems the 600 is also a lighter car, so would benefit from the additional power an 850 engine would have. So I guess my question is.. does the 600 offer any additional performance benefit to the 850 and is it easier to "hop up"? I am thinking of picking up a 600 and have an extra 903cc I could install if I can get it to work.