I bought this Mazda RX7 with 20,614 original miles and it came with a complete exhaust system, dwn pipe, mid pipe and exhaust. The original owner just put the system in about 500 miles before I purchased it. I was told to order the APEXI ECU upgrade which I did for $900 from the Rx7 store. Im confused as to just dropping the new ecu in or do I put it in and then do i need to have the car what you guys call "fine tuned". I was told by the RX7 store that it will be mapped already for up to 500hp and will be programmed to meet my system I have in the car already. Whats the deal with this? Do I still need the system fine tuned or am I good to go after I simply switch the ECU? Thank you.............John