its a simple job, iirc i've a 70amp relay on it, the shop i got the relay from (electrical supplies shop) gave me the commectors for the pins too, sods law states even if you have them, can picture them in your mind as to where they are, you wont be able to find them when you need them!
the worst part is the removal of the nut on the starter, 8mm rings a bell, small amount of space and on the activa i'd guess you'd have the plemum/inlet chamber to get round too?? (i remember how the job on the bx went!!)
muchly depending on the starter feed nut side of things, can be a 10 minute job, the feed wire can be peeled out of the convoluted housing back to allow it up next to the battery, mine sits between the battery and the plate that holds the airbox inplace on the td iirc.
its a worthy job to do on any older car, can give a couple of years extra on the starter,