Here's real data on your inserts. 18 hp loss for marginal noise reduction. The Wilkinson system was "supposedly" designed to remove the significant hp loss created by the original Ansa and Ansa GTS mufflers. Gary Hall cut GTS cans open and removed all the guts which significantly increased the HP. Not sure anyone ever cared about the noise levels from a Pantera as most posts here ask "how to make my system louder".
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