Methods for making polyolefins are disclosed. One method comprises polymerizing an olefin in the presence of a catalyst system comprising a single-site complex, an agglomerated metal oxide/clay support-activator, and an ionic borate. Including an ionic borate with the support-activator provides an unexpected boost in catalyst activity and gives polyolefins with high molecular weight and improved comonomer incorporation. In another method of the invention, an olefin is polymerized in the presence of an indenoindolyl metal alkylated complex and an agglomerated metal oxide/clay support-activator. Use of alkylated indenoindolyl complexes with the support-activators provides improved activity compared with metal halides.