First my almost stock exhaust setup:
Stock exhaust manifold, both pre-cats, main cat, stock y pipe, and two 3-3.5" magnaflow mufflers. Now that had a stock sound, just barely a little deeper. My friend and I ripped out the main cat today, gutted that, expected a large difference in volume, since my first n/a had no main cat and was loud as hell, and my T2 had all cats + turbo and was still loud; BUT when we fired it up, it sounded almost the same, maybe a little deeper toned but almost the same! Are the two pre-cats that restrictive or is something else goin on?

 

the most restrictive cat is the cat that is most clogged.