I would look into an aero turbine. I have tried slp loudmouth, dynomax bullets 2.5's, magnaflow di/do 22", magnaflow dual in/do 14", dynomax bullets single 3.5", magnaflow resonators. Hand's down I love my aero trubine. I have heard great things about spintech but have never heard any on an ls truck. I have obx lt's, and run them with the 3535 aero trubine muffler.

 

im talking about the oval one..... it actually sounds real good at idle...