Your logic is off IMO.
-------//------//-----------/---
exhaust in a nutshell.
1st // = cat
2nd // = res
/ = muffler
-------//-------------------/---
The less restrictions, the better.
Sure, the resonator is not the ONLY bottleneck, but it is still a bottleneck. There will be lower pressure from higher velocity with the resonator removed. And there is a difference between a bottleneck and a restriction...a restriction can be something in the way (cat honeycomb), but a bottleneck (y pipe/res) forces the flow to go from a 2.25" pipe to a 2" pipe, disrupting flow and creating more pressure/less velocity. Hence the term....bottle neck.
