I have the same problem with my CycleOps Magnus. I inflate the tire appropriately, i tighten the wheel until it clicks and I have a hard time keeping up with my group rides at a "conversational pace". I honestly think there's a variance in the way Zwift interprets data from different trainers. And like someone else said, some riders are fast because of what they're using. I know folks that use regular fluid trainers and sail up the hills because their trainer can't mimic that resistance or they just don't add resistance.