There's a product I've used from bigcity thunder. If they have one that are big enough, these work really well on both cars and motorcycles. Although intended for motorcycles, I had a set of borla atak catbacks on my chevy cruze, and put these inside the muffler tube. Tones it down quite a bit. Might not fit in the muffler itself, but could fit somewhere in the tube....
https://bigcitythunder.com/collectio...onster-baffles
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