Several months ago, I installed a new system in my SLS. It consists of an Alpine 9830 HU, an Alpine S634 cd changer and Infinity Kappa co axial speakers. Just the sub needed to be changed. The stock sub is almost unhearable at moderate volumes. It doesn't kick in until higher volumes are played. That is not good for me, as I do not like to listen to music, at really high volumes. So, I just ordered my new sub and amp today. I am going with an Infinity Kappa Perfect 12.1 sub, and a Profile amp. I will say this, it is hard, very hard, to find a low power amp. Almost every amp is rated at 500 watts or higher. I needed one in the 150 - 250 range.I settled for the Profile HA700M Baja amp. It was rather cheap, at about $70.00. So if it turns out to be crap, it won't hurt me to change to a different one. Once I receive, and install the new parts, I will post back with the results.
Don
Don