[Choady]

Also, as Dan in Pasadena said,

Increasing your caster make the vehicle go straighter easier.
think of the casters on a shopping cart, or the forks on a motorcycle.
When the caster angle is increased, the vehicle goes straighter easier.
Unless you plan on road racing, I know you will appreciate the improvement.
(Conversely, less caster makes your steering more squirrely)
Notice how as a kid, you could take your hands off the handle bars while you were riding your bike and still go straight?

Wedges are my favorite, low budget improvement.
I can drive 70 mph on the Freeways here in SoCal and my truck doesnt wander back and forth in my lane. it tracks much straighter.

Thats just my $0.02 hope it helps
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Sorry everyone for being so longwinded.