Mol - I did the same as you and noticed the same improvements as you too. I do believe that the tiny CATs in the headers are a restriction to flow and were what looks like an afterthought, despite always being a mandatory part of the design.
Caterham Se7ens have very good performance CATs on them - but just look at the size of the things! In fact any performance CAT is huge if it is going to work efficiently - which is exactly what the M3W CATs aren't. So top work and if you don't need them for annual technical inspections, then so much the better!
An M3W with high-flow CATs however would look very different, which is what drove the current design of course.
