Not true at all.
One of the quick & easy tricks in the "old days" was to buy an OEM-type muffler for a 426 hemi, 440 six pack, 454, etc. and install it in your 4-banger or small 6. You'd get outstanding flow and near silence. Only issue was you may not have room under the car for the muffler that was likely half the size of your car!
Anyway, the point is that if you can find a muffler intended for a big, high-power engine and find a way to make it fit, you may have just what you're looking for. May or may not be worth the trial-and-error to you, though.