There's a couple of older threads that you should look through:
http://forums.hunter.sailboatowners.com/showthread.php?p=558992
and
http://forums.hunter.sailboatowners.com/showthread.php?p=558851
There were no firm conclusions (might want to check archives for other threads) but good reading in any case.
In my 170, I had lee helm problems when I first owned the boat. For a variety of unrelated reasons, I did the following:
1) Tensioned stays to increase forestay tension
2) Replaced jib. Old one was servicable but far from new.
3) Used sailkote to make tensioning the main halyard easier. Tension was too loose in my early outings.
4) Paid more attention to boom vang
5) Boat is trimmed much better now than in my early outings.
Some combination of these things resulted in much better handling characteristics.
I would also recommend reading up on Don Guillette's literature, sold on this site. Apologies if you already know the finer aspects of sail trim but I purchased and read through his book and charts. Some stuff I knew, some I had forgotten but the rest was well worth the purchase price.