noise from curt hitch

i have a 2002 crv i have installed a curt hitch on it and now has awful loud rattling sound. i have verified the exhaust is not hitting the hitch bolts and it does this at varying different acceleration rpms with or without the ball mount insert installed. when the trailer is being towed it is absolutely deafening and more prevalent. the bolts are all tight and the exhaust is not hitting the hitch. when i remove the hitch the noise goes away, and i also noticed that when the hitch is installed the body seems much more rigid. has anyone else experienced this? any help would be greatly appreciated