Too much stuff to read above so sorry if it has been covered.
I personally think that the 4af is a better driving car stock from stock for it's better torque and the drivabilty around town.
The f series head was designed with economy in mind but there have been a few people test the head after they have done work to them and find that they out flow the 4age head.
Would be interesting to see an actual 4af built with performance in mind.
btw, the 4age starts out with 86kw.