I'm not familiar with a DVR-108AA; it's very likely the same drive as the DVR-108/A08. The 108/A08 is a 16X drive, so either you're not using media that Pioneer has certified for 16X writing, or the Apple firmware in the drive has removed 16X speeds (wouldn't be the first time Apple has crippled the superdrives).
Please post the Hardware->Disc Burning info from System Profiler, so I can see what it reports about your drive. Like I said above, your drive is probably the same as the regular DVR-108.
Since your profile says you're from Ontario (doesn't specify Canada or California), this means that you've got a region 1 drive (for playback). The site you located is one of Pioneer's European sites, and I would be concerned that the firmware from that site might change the drive to a region 2, which wouldn't be desirable.
You should get the firmware from the site that I linked to in my previous post. Specifically, get the one for the
DVR-108. It's a PC self-extracting executable, so you'll need to download it and then extract the files with Stuffit Expander.
Then, you need to get
DVRFlash to perform the firmware update. It's a command line program, although there is a GUI version available which should work with your drive. I have not used the GUI version, however. The directions provided with DVRFlash are pretty detailed, so it should be fairly easy to perform the update. I believe the first time you do the flash, you'll need to force it, as you'll be told there's a mismatch. This is normal, since you're flashing an OEM drive with the retail firmware.
When the update is complete, reboot the computer, and System Profiler should report the drive as being a DVR-108. And, you should also now have 16X burning as an option.
Please be aware that doing this flash will void the warranty on your drive. Should something go wrong, you can end up with an inoperable drive. Perform the flash at your own risk.
I haven't had any problems flashing several of my drives, by that doesn't mean it works perfectly for everyone.
Post back here if you have any more questions. I'm happy to help out.