I've got a MIG. As so every exhaust or body shop...
Im also quite happy with the sound of my new mufflers.
video of the note?
You won't get more power, but you will have less mass to accelerate. The engine will rev up and down much quicker. It will also be more prone to stalling when coming down to an idle, or when starting off. And it will vibrate more as well, simply due to the reduced mass.
Should make for an interesting ride!
I know drewpy used it in one of his 400's with no issues and that a few guys on the german xs400 forum use them in their race bikes.