I recently had my Blemhco BBK installed and I love the results. My question to those with BBKs or any brake experts out there, now that the master cylinder has to push 6 more pistons than originally designed for, shouldn't the stock master cylinder also be replaced also to compensate for the "extra" load?

Was hanging out with some old .org members last night and they were advising that I replace the master brake cylinder with one from that of a Q45.

 

It would be better if you did replace it with a 300zx one. Q45 has two piston up front and single in rear so I dout its master cyl is that much better.

 

Its not necessarily the # of pistons, but the total piston area. I've read that the 4 300zx pistons aren't much bigger in area than the one large stock front piston, so a bigger MC isn't necessary. My car certainly doesn't seem to need one.

 

yup, what he said.
your factory caliper uses a single 2.25" or 2.5" piston.
the Z32 calipers use four 1.59" pistons per caliper. the total piston area is roughly double the stock, IIRC, but it's been a while since I did the calculations.

so far, I've done the swap one probably 20 cars, and none of them have needed a master cylinder swap.

 

That one piston per caliper on our factory brakes is quite large in comparison to those in a 4 piston BBK.