Build quality was great. No problems with it. Can’t really comment on the sound, since I modified mine. I had a resonated Milltek before that was too quiet. So I replaced the resonated Milltek section with the ECS valved section. Still tied it into my Milltek back box. So now it’s like swapping between resonated/unresonated. There’s a noticeable difference in tone, open is a lot deeper. Not a huge difference in volume, but I attribute that to the extra back box.