I know it sounds dumb, but had you provided a PDF link to the manual, I would have looked at it a lot sooner. So for everyone else's convenience, here it is:
http://www.manualnguide.com/dl/4793/
Where do you want me to start reading, or which particular pages? Starting from pg 36 perhaps?
For full disclosure, I've never once tinkered with a Pio receiver, but I can give it a shot to see if I can possibly offer anything worthwhile at all.
Also for full disclosure, just as an educated guess outta da butt, I predict that you're going to need measuring equipment and software to finally know what tweaks to do beyond the basic/auto stuff.