You can get a smaller coil for better pinpointing. I hear the eclipse 950 works better than the D2 coil, and its better in high trash.
I have found i cant pinpoint deep targs good, until i dig the nearby trash out of the way.
You need to find the right ground filter to run in, depends on your ground mineralization. i run 5khz band alot, but im low min.
Make sure you ground balance properly. Then swing low and slow.
There are video in whites forum on how to ground balance properly, etc. Ground balancing pulls your settings together.
Seems like backing down on discrimination helps rid of some of the falsing, but might experience some loss of depth.
Im still trying to figure out my v3i, hope this helps some.