Thanks for sharing with us the Dyno Chart, Video Clips and your experience.
I have a very silly Q but made me wondering, If both mid pipes of the 1M and the N55 are identical except for the 2nd Cat, wasn’t it just easier to cut off the cat from the original mid pipe of the 1m and just do some good welding job with a piece of straight pipe ?
Now, since you gained around 22 HP, what is next on your mind ? will u go for ECU Flashing ? downpipes ? Bigger FMIC ?