I really like the fact that the QS is a few pounds lighter, but the stage two is flush to the difuser which won't slow down the exiting air. I would really like to see a comparison dyno of the two. Maybe one of the vendors can volunteer the product. We can use my car. Is quicksiver coming out with a flush exhaust? Also, we should be measuring my car soon for the RAC wheels that sector 111 will be offering.