Best deep muffler for 5.7

[L31MaxExpress]

This is what I have on the 1987 G20 with a ~400 hp L31 in it. Thorley tri-ys, Walker 2.5" cats and this muffler. Sounds great IMO and zero drone.

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What it sounds like at 75-80 mph and climbing a steep grade. That 1,000 cfm 4150 throttle body has quite the growl. Phone was basically over the engine in my suction cup holder on the windshield. The secondaries start to open at about 65% throttle, power enrichment comes on at 50% throttle or under 7.5 in/hg vacuum.

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[L31MaxExpress]

For wide open throttle max HP the large exhaust pipes are best. For low to medium throttle driving smaller pipes will give better fuel mileage and throttle response within reason. For example a 350 with a dual 3” will have a higher peak HP than a dual 2” but the 2” will give better drivability. The happy medium being dual 2.5”.

My 97 Express 350 had dual 3" pipes from GM. My 99 Tahoe had the dual ~2". I can say NONE of that was true atleast for me. The Tahoe was a fuel drinking slug and way down on power. The van had much larger cats on it as well.