When I had the W4 (I believe that these and the "R" version are sonically the same, correct me if I'm wrong), I thought that they lacked the excitement in the bass department. I sold them and got a pair of TripleFis. Bass was there, and yet, still no grit. So, I moved to customs. UM miracle and yet, I didn't feel that bite in the bass guitar, or the flow of air in my head. Until I tried dynamics. A pair of Miles Davis Tributes and JVC fx700 later, I realized that Dynamics and BAs work in very different ways. The BAs may be more articulate and layered in terms of a sophisticated presentation, but I've yet to come across a pair that offers me the "headphone in your ear" feel. Dynamics can move air around, giving the bass a more lively energy.
In response to the OP's question, I think the W4(r)s have a very adequate amount of bass, which is excellently textured (I remember The Prodigy sounding wonderful), but if you are looking for that "slam", you'll have to look towards a more bass-orient BA or move to a dynamic.