If I had to choose a second cheap car to upgrade i would have to get a 99-00 civic hatch back and swap either a Integra type R motor into it or if you wanted to spend a little more money you could put a K20 aka Rsx type s motor into it and it would really move then. Don't much like the DSM's or the 5.0 mustangs. Second choice would be the 240 sx and then third the MR2. but it is really up to what you like. All can be made fast pretty easily.