Thanks All. An interesting mix of suggestions.
My home is literally 20' x 20'. I call it my "little cottage". Seven foot ceiling and no basement. Therefore, my living room(10x12) is my listening room. Speakers on each side of TV and very little room for optimum placement. Especially those Ultra Towers. If I could "unbuy" them I would. When I stated "highly modified" this is what I did.
As you all know, many well established speaker companies skimp on the internals and SVS is no exception. Very disappointed when I opened them up. Basic components on the crossover. Binding post crap. Wiring type questionable. I updated the crossover as much as I could and still get them to fit inside the cabinet. Clarity Caps. Ribbon and Litz coils. This was done only on the upper and high frequency parts of the crossover. The inductors I wanted to use for the bass part are just too big and an external crossover would be needed. So, yes, probably my own fault for the bump in db in the 4 to 5k range. I do not have access to proper testing equipment so it was a "guess" . But I figured anything would be an improvement to what SVS used.
The cheap binding post is replaced with almost pure copper type, the company name alludes me at this time. Used VH Audio hook-up wire and Cardas solder. I added dampening to all the cabinet surfaces.
The result was worth the effort. Not going to bore you with all the blah blah of soundstage and such.
Sure wish I had a dedicated listening room but heck, My rent is only $350.00/mo. and that includes heat and electricity! That is a big plus here in northern Michigan.
I'm leaning towards Triode Wire Labs.