That's effectively how most (all?) decent SSD's work these days. Internally they use multiple channels in parallel (think RAID-0). The performance you see externally for a single device is as good as it gets for that device; the only way to increase performance is to use multiple devices.
For a good overview of why what, and how, see http://onfi.org/presentations/
(ONFI is the Open NAND Flash Interface organization).