Bought a 96 GSR back in March as the 2nd owner. Everything is bone stock on this car, down to the radio. The car has been making a rattling noise around 3000-3400RPM range. Running on the highway for two hours mitigates the sound a little. I've taken some of the exhaust shielding off around the cat, but the noise is still there. This leads me to believe this is the shielding around the exhaust manifold. This is really annoying, especially driving in town. Do I just need to buy an aftermarket header? Does anyone have this problem?