I like stringing one of my Stingrays with heavy gauage strings. However, I'm not very fond of Boomers. Are they the only company that makes 115-55 gauge strings? I need to try somebody else damnit!!
there's Ken Smith NPS r/w's (60-115) -- http://juststrings.com/ksb-aa-bbxh.html ...maybe these wacky s/s r/w Rotosounds? (130 E ) -- http://juststrings.com/rts-rs66lh.html
Those Smith's that notduane mention seem to be as close as you'll get without going the single-string route. If you're dead set on that exact gauge, try SIT Powerwounds. They make a variety of singles including those you're looking for. JustStrings has em. Tom