Too much air pressure in the front tires rounds out the contact patch and makes the bike twitchy.
The bike sets up "on the balls of it's feet" and becomes too sensitive to anomalies in the road.
Having too little air pressure flattens the contact patch making it relatively more difficult to turn, but the bike is more stable.
For myself, I've found about 18 PSI is good while using the stock Kenda. I don't know what might be a good pressure for other brand tires.
If you are around 17 to 24 PSI and the bike feels like you're constantly riding behind a semi truck, then you most likely need a laser alignment.
A properly set up Spyder should track like it's on rails.
If not, something is wrong, either an alignment, or perhaps one of the suspension components, such as ball joints.
I don't go for the "loose grip" theory. Trust me, I went through that same journey in 2010 when I first bought my Spyder, and no one had any experience with them.

http://www.spyderlovers.com/forums/s...hlight=journey

Of course, that's my opinion. I could be wrong, and I'm sure someone here will let me know if I am.