the vehicle will sound differently under a load then it will in nuetral. revving it up in nuetral isnt the best idea either. i have an LS with dc sports 4-1 header random cat and tanabe race medallion catback. its loud as hell but esp when i hit 4-5G i hear a loud raspy noise. it is just the violence of the gasses coming into the collector and throughout the exhaust. i wouldnt strip the shield above the cat. the cat gets really hot you dont want to risk melting anything.