Brake bias/rear tires lock up with front Brembo caliper

[motronic]

I upgraded the front caliper to 350Z Brembo but now I have issue during hard braking the rear tires would lock up first and potentially creating dangerous condition.
I bled the brakes twice, pedal actually felt good, checked the lines for any kinks. I would think the combination of larger front rotor, larger front pads, larger piston size would shift the brake bias to the front but the contrary happens.
I have Brembo calipers on the front, Stoptech rotors all around, Z32 rear caliper, 1" Z32 Tokico BMC and Z32 brake booster. Pads is the same all around, Hawk HPS.
I am out of ideas, I am thinking of replacing the BMC at the moment but I am not sure if that is the culprit.

[gunluvS14]

Hmmm, that is weird. Z33 front and Z32 should gives you 68.6% front bias.
What's the split point of that 1" Z32 BMC?

what's your alignment setup and suspension? most importantly, what kind of tire and tire pressure do u have in the rear? I really doubt this is a brake bias problem. It could be suspension/tire related.

[motronic]

Hmmm, that is weird. Z33 front and Z32 should gives you 68.6% front bias.
What's the split point of that 1" Z32 BMC?

what's your alignment setup and suspension? most importantly, what kind of tire and tire pressure do u have in the rear? I really doubt this is a brake bias problem. It could be suspension/tire related.

The split point for 1" BM50 Tokico that I have I believe is 369 PSI which already is the lowest compared to other BMC options. Which makes this really strange since this would give me the least rear bias.
Tires are RE050A 245 front and 265 Rears, suspension is Nismo S tune all around, tire pressure is 35 all around.

[fueled by hate]

Maybe there's a stock proportioning valve that you can adjust or you might have to add one like this.
JEGS Adjustable Proportioning Valve - JEGS (http://www.jegs.com/p/JEGS/JEGS-Adjustable-Proportioning-Valve/755192/10002/-1)

[motronic]

Maybe there's a stock proportioning valve that you can adjust or you might have to add one like this.
JEGS Adjustable Proportioning Valve - JEGS (http://www.jegs.com/p/JEGS/JEGS-Adjustable-Proportioning-Valve/755192/10002/-1)

I thought about that, but somehow I am not convinced that this will work very optimum with the current split point and stock proportioning valve.
I put new remanufactured BM 57 BMC 1 1/16, re bled the entire brake system and still have the same issue.
I am beginning to believe that this setup does not work well at all with S chassis. I may just go back to Z32calipers all around.