Stock Brake Problems

[240 2NR]

First my specs:

93 240sx SE fastback 63k miles
Stock calipers
Stock rotors
Stock lines
KVR carbon kevlar pads
ATE Super blue brake fluid (also used valvoline synpower, and stock fluid with same effects)
Stock MC, and brake booster

The Problem:
My brakes have never felt right.  When cold it feels like I'm squeezing two bricks against my rotors.  There is little bite, though they do slow the car, but it's nothing special unless I really stand on the pedal.  This is how the original pads felt as well (changed by previous owner, unknown type, 90% pad remaining, even wear so it's not a seized caliper) and the
motivation to replace all of mine with the KVR's.  Still the same feel.  

When I do depress the pedal hard it feels like I'm either flexing the pedal arm or the lines, as it will go a bit further, but feels more like play than additional stopping power (almost like it's pushing back).

The odd part is once the brakes reach a magical temperature they bite like crazy all at once and then hold that performance.  I've run these brakes at the track and love them once hot.  No fade so far, and insane grip from such
a puny braking system.  This problem is defintely not warm up time, though it may be increasing the symptoms.  I've been in other cars with these brakes and it doesn't take as long to warm them up.

I can find no leaks anywhere in the system, the fluid is fresh, the MC and brake booster look good, the pads aren't glazed, and the resevoir is topped off and doesn't go anywhere.  My only other thought is that the rotors are a bit scored.  Running my fingers over the rotor surface you can feel they
are uneven (condition that existed before the new pads).  Could this be the cause of my pedal feel/ poor performance?  I'm tempted to try new rotors (though mine are all at least 1.5mm over min spec) to see if that solves the problem, if not then I will try a new MC, but it seems like money wasted since I plan to get Z brakes next year.  At the same time I want to fix this if it's not rotor or pad related as it will still exist with the bigger brakes.  Eric Johnson has also driven the car and agrees that they don't feel right.

I'm ruling out lines as other 240's have felt better, and really starting to think it must either be the booster, MC, or the rotors.  Anyone know how to check the vacuum pressure?

Thanks in advance, <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/hehe.gif" border="0" valign="absmiddle" alt=':hehe:'>