Today after some troubles experienced by a member/friend regarding re-tuning Unichip, I did some Googling and there are many links on the subject However the following two are the most relevant and accurate (IMHO) that I hope may provide some useful info to members here.
Standalone ECU vs piggyback :
(1) http://forums.superstreetonline.com/70/1010816/ecu-tuning-electronics/engine-tuning-standalone-ecu-vs-piggy-back-ecu-eng/index.html
(2) http://www.lotustalk.com/forums/f25/piggyback-standalone-ecu-options-turbo-elise-25946/index2.html
It was actually very hard for me to understand some of the stuff discussed/mentioned in the above two webpages, and it is even harder when considering that I actually have no real hard knowledge about our Lancer's ECU.
Suffice to say, from the above 2 webpages and from some further research I did, I believe that such computer management CANNOT take advantage of whatever exhaust setup you may have. IOW, post-combustion (i.e. your exhaust) really cannot be of any real use for aftermarket computers beyond the tuner knowing what is a stock car's AFR, the exhaust AFR info from which he will start messing around with the AFR.
IOW, it is very likely that many (if not all) will first alter/mod their exhaust FIRST (or other mod stuff) and then add on a piggyback/ECU. I believe the better way (which is time consuming, and prolly very expensive in terms of experimenting or finding the absolutely correct/perfect mod stuff incl exhaust) would be to buy a piggyback/ECU, get the stock readings, consult with tuner WHAT HE KNOWS ABOUT OUR ECU AND OUR ENGINE and then go look for the best possible mods.
I did things the other way around i.e. buy/install mod stuff first and then install Unichip.
This is just my opinion and hypothesis, I could be wrong. Feel free to read the 2 webpages I posted above, think a bit, do some reasearch and see if you agree with me.
I think in order to save moner we must get to know a 4B11 engineer