Today I got the opportunity to mess around with the XTZ analyzer in my Lexus. You can read more about the unit
here. It's a self-contained RTA and node-finding analyzer which comes in really handy when squeezing every last ounce of potential out of you system. You download the software from XTZ's web site and then you use your computer to power the mic via a supplied USB connection. The signal used to measure with comes from an RCA output jack on the base of the mic. I piped this through my system using the Aux input on my Eclipse 7200.
Now, the bass knob was turned up a little bit, which is why you'll the rise at/around 100 Hz. But dismissing the rise, which I can take care of on the fly, the result was pretty flat. I took care of the minor peaks with the 3sixty.2 after these pics were taken. Come to think of it, I actually did a lot of EQ work after these pics were taken. But you'll get an idea anyway.
These next pics are BIG!! I had the setting wrong on my camera and I don't have a program to re-size them. Sorry. 
The software also comes with a waterfall plot and a standard frequency response display for finding nodes in your listening room. In this case, I used it to find out where the SC 400 has issues due to the interior acoustics. The nodes I found were exactly one octave apart (which I expected - nodes can be found in octaves some times) at 31 and 62 Hz. Here are the pics of the two responses:
As you can see, they don't show up on the RTA at all. I actually left 65 Hz alone on the RTA because it was level. But testing for resonances and/or voids, I found that 63 and 31 Hz are heavily affected by the vehicles interior acoustics.
It's just neat to test this kind of stuff and gather information.
