I have purchased both systems from them. The Transverse system is quite a bit cheaper, and sounds better (my opinion). I have a gardner chambered system that was on my Z for about twenty miles of use. Too loud for my taste but certainly has the wow factor. My yenko has their transverse system, and is very quiet. My L34 has their chambered and it sound very nice, if you like the glasspacks. I have an orig GM chambered system that I plan to install on the L34. It should be interesting to compare the GM to the Gardner.