These bolts have a 'seat' under the head that goes into the flexplate and align it and fit very snug. Spend the money and get the OEM bolts, especially considering they're not easy to get to and are in a place you don't want a bolt to fail. At the least, you may end up with vibrations.

Cheaper: https://www.*******.com/products/mercedes-clutch-flywheel-bolt-1089900419