I removed the precat on my Edition 30 yesterday. The turbo pickup difference is amazing - far faster pickup and it sounds better.
The exhaust note is a lot more 'burbly' too and sounds great, really nice when backing off the throttle.
I can report more on mpg later, at the moment it's definitely better but maybe only by 2 mpg. I did my usual route to work today where I always get 33 to 35 mpg. I got 36 mpg for the first time ever, but was driving slightly faster today. So it's good.
I reused all original bolts, nuts, and gaskets.
It's a difficult job on the driveway and took nearly 3 hours, not including food and drink breaks. It would have taken less time had I not dropped a nut into the engine bay... and then a socket. Both of these each took around 30 minutes to locate and recover. lol
The penetrative oil is a must for releasing any seized bolts/nuts.
So in my opinion it is absolutely definitely worth doing.