Also, to be on topic with the original post...
People have swapped out batteries in there systems and monitored the voltage. Currently, XS Power makes the best car audio battery out to date. People have done direct swaps of the same size batteries, most commonly Group 31 batters, and have saw less voltage drop when using an XS Power. Voltage is everything when it comes to car audio. When you clamp your amplifiers output, you have to factor in your voltage drop. The reason being is because amps will put out more power if the input voltage is higher.
Higher voltage also leads to a cleaner signal. My next real world use with a clipping indicator on my mono amp; With my stock alt, my voltage would drop to 12.0V and on would clip say volume 25 on a certain song. Now, I can hold 14.0V with my new HO alt on the exact same song and receive no clipping. Now if I disconnect one or two of my batteries in the rear, my voltage start to sink severely and once again I'll receive the clipped signal.
For those of you who don't know what a clipped signal is... Picture this, a sine wave is the wave a speaker produces assuming the signal is clean. The coil inside moves in the shape of the sine wave. The crest and the trough is when the coil builds up the most heat. A clipped signal produces a square wave. Look at the difference between the peaks and troughs of the square wave to the sine wave; The square wave (clipped signal) produces WAY more heat due to the coil stay at the crest and trough much longer. Coils over-heating is the electrical limit of subwoofers which will cause them to blow.
In summary, from my experience, along with EVERY other competitor I have competed with, including at the DBDrag World Finals, the more battery, the higher the voltage, the less clipped signal, the safer your system is. Also, on the meter, most people lose tenths of decibels burping a clipped signal rather than a nice clean signal.
Edit* I'm talking about daily. Most of us run daily cars but compete with them too. The difference between a burp vehicle (what you consider a competition car) and a daily car is all in the tuning of the box. Most cars running a burp setup tunes there boxes around 50-80hz and can't play music. Daily, we can play music and put up some loud numbers.
Edit 2* Also, a lot of leagues compete car on. The most prestigious classes in DBDrag, such as the SuperStreet classes run car on.
