I once called summit customer service about a part misfit. It was designed for my year of engine, but grossly didn't fit. They tried to track the part number, but couldn't find it in their system. Come to find out, I had bought it off amazon, not summit, months before and forgot! The service guy, still helped me get the manufacturer's info and number to fix the problem! These guy's are the best!
As for mail, if my order is in before 3pm west coast time, it's here by 10 am the next day! I'd have to say they are the best company consistently that I have delt with! They always stand behind thier stuff and are always curtious.