12.4 to 12.6 is what I aim for too. With NA's you can head towards 13.1 without an issue but it depends on how much timing your running and if it's prone to detonation which the 1UZ should be.
By running big ignition timing at 13:1 af, which puts it close to detonation you can then bring the af ratio down further to say 12.5:1 and stave off the detonation with the extra fuel which removes heat from the intake charge.
That's maybe what your tuner is doing. It's best to do timing to the point of detonation first and then add fuel to give you the safety margin and drop back the timing 1 or 2 degrees then you'll be running at optimum with a safety.
Sun, 25 May 2003 05:37
