Many cars come to mind:
Subaru LGT
Altima SE/SE-R
Mitsu EVO
WRX STi
MS6
BMW 325/328/330/M3
I'm not sure I'd invest in the 3L conversion, YMMV however. You end up with a car that is difficult to work on, highly customized, older, and in most cases not even as fast as most of the cars listed above bone stock, with little to no aftermarket available, whereas with the cars above, you start out in a much better position, and can go faster from there.
