im getting a really bad rattling noise from my exhaust system especially and low rpm and mid-high throttle (10inches of vacuum). i have had a look and all exhaust components seem good. There is no broken bits in the mufflers. This all started when i gutted my cats, i did put a straight through the cat shells to get rid of the echo. i have been told that the rattle could be due to the exhaust design. Has anyone heard of this before, if so, do you guys know how to fix it