Hi there , I just got mine RX-7 FC others are oringinal spec . (90'S) http://www.bomexaero.com/images1/fd/fdam.jpg
http://www.bomexaero.com/images1/fc/DSCF1545.jpg
The AD kit

What ECU should i change to improve the performance ?
Should I move the intercooler to the front ?

Ps: I just replca a "Toyo" Alluminum Radiator .

I'd leave the top mount intercooler there until you get some mods like a larger turbo. As for the ECU, I'd do that right away. I prefer engine management systems like haltech, aem, microtech, etc but if you just want a drop in replacement you can get something like the knight sports chip. Plenty of places make an affordable chip that will effectively eliminate fuel cut at 14.7 psi.