its not too bad on a 87 turbododge ecu (what i run). just socket it, pop in a 27sf512 with a different calibration on it and its a go. the 88-94 ones you have to carve out this epoxy stuff that similar to silicone. ostrich works well too though I havent bought one yet.
there was no 2.5L 87 ecu (just 2.2L) so I had to copy many of the tables from 89 2.5L computer and then scale them all for the 3-bar map and the 52lb injectors. then since the factory stuff never went over 14.7 psi (2-bar map) anything over that had to be changed as the timing never ramped down as the boost went up and it needed more part throttle fuel. it has a launch rev limiter now too (under 2-3mph from the speed sensor) and the check engine light blinks when there is knock from the factory knock detection setup (individual cyl retard).
Brian