I took my car to my local muffler shop earlier this week for them to fix a rattling noise from underneath. Apparently I scraped my underside and knocked the passenger side muffler loose. They later called me to tell me that many of pipes were in bad shape from being constantly bent and banged. The structural integrity of many of the pipes were bad and that they offered to replace them and tuck the pipes better underneath my car free of charge. I told them to go ahead and do so. Well I pick up my car later that day and on the drive home I noticed that it was noticeably quieter. Even my brother (who is an aspiring mechanic) said the same thing. First thing I looked for was to see if they had replaced my midpipe. From what I can tell its still there. So what maybe the cause of this? I saw on the mechanic notes that they used 2 1/4 outlet pipes. Are they supposed to be 2 1/2?