Hello, I recently just had to replace the short motor in my 02 STi, replace the gaskets and get the heads reconditioned. I ended up upgrading from the ej20 STi motor to the ej25 STI motor. Since I got the car back it's been using quite a bit more fuel and I figured I'd need a retune but will I need a new ecu to run the bigger motor properly? It currently has a Denso ecu, i'm not too sure what model, it has 4K at the top, then underneath 22611AH180, then under that is 112200-2581 12V (I'm guessing that may be a stock ecu?). Will that ecu run it properly or will I need a new ecu? If I need a new one, what would be a good one to get? Another question I have, slightly off-topic but what exactly is flashing an ecu? I'm failry new to this stuff, thanks in advance.