I installed the Ansa cat-back system on my '88 528e over the weekend and found that the Ansa system is more quiet than the Bosal, but the Bosal system is built much better. This is consistant with what others on the Forum had said. The Bosal system bolted right up with no hassle at all, the Ansa system didn't fit very well and had to be "massaged" a bit. Just FYI.