Performance Certificate (a.k.a. Birth Certificate)

Anybody know how reliable these hand written certificates that state THD, Signal-to-Noise Ratio, and Power Rating have been tested (by an actual tester) are? I my MTX Thunder6500D today and it came back with some surprising tests results (601W RMS into 2 Ohms at 12.5V even though the manual says 500W RMS into 2 Ohms at 12.5V) Is it for real (It is filled out and signed by hand)? How reliable are these spec sheets? Not that I bought that amp because I was expecting more power (I don't even need half that power, hehe). 

                                                                                               Thanks, Colin a.k.a. bLaZ

Run the first one with the car(12volts) off and then turn your car on. You should get between 13.8 and 14.4 volts

alot of amps wont run on more than 15 Volts, so higher voltages than your alternator NORMALLY produce wont do you much good...you can buy alternators with external voltage regulators and you can buy adjustable external regualtors that will let you crank out 16 or 18 Volts...alot of SPL competitors are doing this...running 16V systems with sets of 8V batteries...

but as far as going from 12V to 14.4V, that is your car...your battery runs at 12V when the car as off, but the alternator puts out (typically) 14V and that is what your system sees when the car is running...