I use Xelastec on both Serial and Volt. They have a wide bore.
What I realized, after reading a post that I cannot locate, is that the tips do not really improve one range or another, what they do is cut frequencies compared to if I had the earphone without a tip. Cutting the highs and mids, for example, can seem to increase the bass. In the end, what I decided, and it works well for me, is to try to make the sound output as clean as possible, that the tip affects as little as possible, and if I want to touch up any range, I do it through EQ. That is why the Xelastec suit me very well, and contrary to what some people say, they are very comfortable for me. In addition, the silicone is moldable with the heat of the inner ear, and once put on, they remain adhered, and do not move.