In the year or so that I had 187s, all my tests showed that 187s fared OK with power that low, but really should be properly fed with 400 to 600 real watts. Of course if you have the ability to use more than ~2 cubes / sub the output could change drastically.
One thing I do know is 1 year, small sealed boxes, big sealed boxes, small ported boxes, Decware Deathboxes (FTW, BTW), and a "Tottie Edition" MTX 1501D couldn't do more than properly break in the suspension of my 187s. I sold them and they still played like I'd only had them a month.