As I mentioned earlier, most are 1/2", as are mine. My pump has been in since at least 1998 when I bought my then-12-year-old boat. I have no reason to believe that it isn't the pump installed by Catalina in 1986, but even...Who knows, perhaps if Catalina simply increased the pipe size marginally on the suction side, these pumps would last forever. It's not like they are working hard at all, yet still they seem to have a limited service life.
Among the first things removed / checked on the pressure side (along with the pre-feed strainer on the supply side).Faucet Aerators come with different flow rates. I believe they are color coded. Reading the above I was unsure if you have already looked at these. On my boat I am going the other way, trying to reduce flow rate to conserve water. Aerators are made to accomplish this.