Only got the front one on so far but I would say about 8, 10 would be a bigger whiteline bar (just get 33gtr whiteline if you want bigger). For the ~$50 per bar, excellent bang for buck upgrade!
With only the front on, turn in is very noticably better, steering is slightly heavier and there seems to be a tad more understeer BUT, I also put the tight as fk shimmed LSD in at the same time SO I actually think the push (understeer or tendancy to wash out in bends) is due to the diff as I have had to change my driving style to more like I drive the 32 with the 2-way.
Once I get the rear bar on, that should counter the slight push* and make it even more tail happy (hiflow + 2WD + LSD = super happy fun sideways time).
*Note: the push is only noticably when maintaining a speed round a long sweeping bend (and that feels more like the diff), or at like 2km/h when chucking a spewy.
P.S. welcome to come for a ride if you want, might even let you behind the wheel