So I'm running a 1jz non vvti in my mk3, has a fmic, 3" exhaust all the way back, pretty much it. This is my daily and I would like to make it a little faster. My plans were to keep stock ecu, injectors(380cc) , get something in the size of a GT35 or similar, maybe get a AFC to adjust full throttle in case I run to rich.
The main thing I don't want is to run rich or lean while regular driving, and on stock injectors I should be fine. Under full throttle worst case I could adjust it with the AFC and take out some fuel if its running to rich.
Here's the second option: I recently met someone who is running a 1jz non vvti, 6266 which is similar size to what I want but he's running @21 psi, stock ecu, with the 440 cc injectors from a 2jz, he has an afc but has not done any fuel adjustments. His AFR aren't rich nor lean regular driving, they are perfect and stay at 14.5-14.8, just like mine on the stock twins, only thing is he tells me is when under full throttle, he goes rich, down to the 10's which is understandable, if anything I would do the same except just take out some fuel with the AFC.
MY QUESTION IS:
Why isn't his car running rich when just regular driving, the ECU still thinks its on the stock 380cc injectors, so when he upgraded shouldn't it be dumping more fuel overall, even when regular driving?