I have a Jet chip in my ECU on my '87. I'm kind of mixed on the results of my chip on my basically unmodified engine (exhaust is the only thing non stock).
I got my chip for cheap with a reman ecu and for what I paid, I'm happy with it. It has a tad more power to help with the difference of going to bigger tires than stock. It feels like it's gotten a little bit of it's pep back with the chip installed. I know that the shift points seem different but really I think that might be in my head..it's TV cable operated IIRC. Although, Jet does say that they modify shift points..
I guess what I'm trying to say is, if you can find one cheap like I did, go for it...No harm no foul if you found that it does nothing. I wouldn't spend full price on one unless I've done EXTENSIVE work under the hood of my engine. Even then I would be hesitant.