Base -> Sport Brake Upgrade = First 25% of pedal is barely any braking
 

Just did an upgrade from Base to Sport brakes. Stainless steel lines all around. Even did the z1 master cylinder bracket that is supposed to firm up the pedal. Bled the brakes with the Motive Powerbleeder in the 16-20psi range.

I've read the other thread like this, where the guy had to bleed his brakes like 5 times and it finally fix it. I've done that same process, pretty much put 12 500ml bottles of castrol dot 4 through it, then another 2L of ATE typ 200 yesterday. I'm absolutely positive there are no air bubbles. This last time I didn't get a single bubble out of any of the 8 bleeders and I left them open for quite a while.

My braking power is pretty good, I'm using the powerstop z23 pads that several corvette reviews claim are pretty much identical to the 1521 pads. As long as I get the pedal down almost all the way I can make ABS kick in.

My questions:

1) When I first did the conversion and changed the lines and everything the master cylinder reservoir definitely got below min (i didnt see a way to avoid this). Some cars need the master cylinder or brake booster bled too, can I do this on the 370z? Maybe there's air in there?

2) Maybe I just need to adjust the pedal so it engages earlier? Is there a way to do this?

3) any other suggestions people have?

I had the same issue. I couldn't figure it out but I would recommend bleeding it multiple times. That should fix the issue.