yea my intake does that at low rpm's even though all the bolts are on hella tight. i just bought some self adhesive cushion padding. they come in 1/2inch x 1/2inch pieces. i put them in two spots where the intake tapped against the body of the car and it stopped tapping and rattling. i guess u can do the same but with bigger pieces of adhesive padding and stick it where ever ur exhaust rattles or comes in contact with parts of your under carriage.