what is 87 and 91 octane going to do for you ? You should be able to do that now. My car runs perfectly on regular fuel. Can you just get a speedo calibrator, and save a bunch of $$ ? Later on down the road depending on what mods your are wanting you'll really want to have your car dyno tuned anyway. I seriously doubt a tuner will use the microtuner. Some chips like my Autologic (which are commonly dynotuned) have a flip swith that can run multiple tunes for different octane fuels like what your want also (for what reason I'm not sure). The EFI solutions reflash work well also, but are 100% best with a dyno tune also. I'd ask here to be sure that's what your want - http://www.modularmustangs.net/forumdisplay.php?f=43
Just a suggestion, seems like a lot of money spent to change different octane levels which you don't need to do. How much are those things generally ? My dyno tune was $460 w/ the chip that can be re-dyno tuned for $260 anytime (like after my blower install)
those are the forums on www.modularfordpowerhouse.com (T & J Performance)
I would think this over. there are better products out there. I would get an sct 4 postion chip. then upgrade to the sofware later. give you full control over your car rathing than just tire size, gears, timining, and a supposed tune. I think the micro tuners are just a band aid. once you really mod your car the tune is garbage becasue it is built for a stock car.