I recently had installed Reus Audio's Upgrade to the factory Bose system for my SL55. It is Ten-thousand times better than the factory audio. Reus Audio is very professional and I am pleased with them. I am enjoying the upgrade, but I am ticked off that you spend this kind of money for a SL55 and the Audio system is not on par with comparable or even lesser automobiles. You then have to spend even more to make the system decent. If you have never had a great system, then you may not notice the difference. But once you have had an excellent audio system, you will notice the difference.