In an SID experiment, mass-selected precursor ions are accelerated to a specified KE before colliding with a surface. Upon impact, the kinetic energy of the ions is converted into internal energy, leading to fragmentation. Upon SID, both clusters demonstrated the same two major fragmentation pathways: a) the two-step sequential loss of ammonia and sulfuric acid, and b) the one-step loss of ammonium bisulfate. The experimentally measured energies required to induce the loss of ammonia and ammonium bisulfate from the clusters always exceeded the theoretical predictions, suggesting the existence of a reverse activation barrier for the addition of these monomers. Loss of sulfuric acid was kinetically controlled, suggesting that growth by sulfuric acid is not barrier controlled. Accommodating an ammonia molecule requires a considerable rearrangement of the electrostatic interactions within the sulfuric acid-rich cluster, and a similar phenomenon was observed for cluster growth by the addition of an ammonium bisulfate molecule. The presence, and height, of the activation barrier to the addition of ammonia to a sulfuric acid cluster can impact cluster distribution in the atmosphere, making it an important detail to account for cluster growth models.