I have been looking at the TDI for at least three years, what mods have you made, if I may ask. The most visible problem for me is the seat, but that is another story.
Check Fred's TDI club. Excellent info on TDI's along with the many problems and fixes.
This is the beginners forum.
http://forums.tdiclub.com/postlist.php?Cat=&Board=UBB35
Also, after the fixes, the TDI is an exceptional car. Love mine.