www.silencerresearch.com shows that the 1.375" diameter suppressors are a bit quieter than the 1.25" cans. HTG Silencers and SWR both have the 1.375 offerings. I've got an HTG Cycle 9 on the way for my USP9SD. Given the tall sights, the additional diameter shouldn't be much of a problem. If you haven't dealt with silencers yet, they are a blast, but backstop and target material matter...the closer and the harder, the louder everything will be. By the way, silencerresearch.com also has some videos of the USP firing with cans on.
agreed.....i still take everything with a grain of salt. btw, he'sIt's a good site but the owner is kind of a nutbar. His testing method is ok, but some people still argue over it. His forum manner outside of his site is atrocious. Take his numbers for what they are, but I don't even bother to read his conclusions.