Totally agree with Yeros. Take the one with the least amount of rust, preferably one without rust. The CSi has been said to be more desirable and has more power, and they are all gray market imports. It is not mechanical, but it is the first EFI that Bosch came out with (D-jet) that measures the manifold pressure to signal to the computer. It is not without its own problems, but once all the variables are in good working order, the car runs great. Also, don't forget that a lot of people convert their CS into a CSI using a later style injection system like the L-jet or Motronic. So, that is why we say a rust free coupe is much more desirable. Tell us in more detail about the two cars and we could be more helpfull.