Would you like to improve the performance by shifting the balance point towards the front or would you like to push it back?
IF you would like to move the balance point forward, use the 3/8" x 16 headless bolts. They are available at Atlascuesupply,com for around $2.50 for 10, each are one inch long and weigh in at .34 oz. You should also spend the $4.75 on their long hex wrench. Don't forget shipping of a few hundred or so, just kidding.
IF you would rather push the balance point to the rear, go to home despot or any hardware store.