there are a lot of little things they do that the econo boxes simply don't have.lots of sound deadner for one. body insulators are better quality as well as the engine refinement and engine mounts.i have added close to 100lbs of sound deadner to my car and it's made a world of difference.
2010 Vibe & member of the yeargarage Email me if you need to talk to me, click my siggy and send the email threw the contact page.