I'm sure someone already covered this, but in case they didn't....
NEVER, NEVER, NEVER change your product, EVER!!!
Here's a couple reasons to get you started....
The "New" Coke vs. the original recipe.
KC Masterpiece sauce before Clorox bought it vs. after they bought it.
People come back to you for your product. They expect the same thing. Consistency is important for a reason. If oyu change it, your regulars will simply ask if they can pay more for the "older, better stuff", and then your new customers will never realize you were as good as you were. Your old customers who know how good your product are will eventually leave out of simple attrition reasons, so you need to keep attracting new customers.