SVS Sounds offer some outstanding non-powered versions of their powered cylinder units. Very well regarded as some of the best available for the money. I have used VMPS in the past as well and having used both brands I can personally suggest you look at the SVS first. VMPS are also excellent but can challenge the WAF with their size and styling. Their approach is the basic physics of bigger is better rather than apply equalized power in a smaller box like you see in the Sunfire subs as an example. Personally I think the VMPS have become dated in their driver technology and just can't keep up with today's serious drivers like what you find in the SVS units.