What is the benefit of changing the secondary clutch spring on my 00TrailBoss? Just checking out all the options.

 

Changing it to what?
Going with a softer spring will allow the belt to sink further into the clutch easier, which means it will be upshifting sooner. This would probably give you a little better feul milage.

More likely you would move to a heavier spring, which would keep you in low "gear" longer, would raise your rpm at most given speeds, and makes the bike a little peppier.

I think I would change the helix rather than the driven spring, though changing your primary spring might be a good idea.