The 231 is a 4 port motor, the 23pum, 230 are 2 port motors. The 260 and 231s are the "newest" Of the 4 port motors in the marine motors.
THey both perform well, stock or moded.
The 231 revs higher than the 23s stock or moded.
231 verses the 260 STOCK, run both the 231 will out rev the 260...