Max a 16v 4AGE can be tuned to?

[Uzelac]

You are forgeting silly little thing called start cost .
BT is like 1000e more expensive and needs fabrication to get into AE86 chassis. Just for putting in an BT in Hachi you can get pistons, cams or itb's.

Of course, noone sane would swap an BT with 16v, but if you start with 16v, and we all have bluetops at the begining, i think it's better to crank up 16v.
Swapping to BT and then tuning it is most expensive option.