You can change to about anything and not change the computer. You just miss out on power by not doing the ecu reflash at hte same time. I've got a couple of used slip-ons and some new options.
For used I currently have 2 sets of CS1 Vance and Hines systems. One nice set and one not as nice. I may have more used options coming in soon as well. Of course I also sell new systems (voodoo and Hindle for example) Usually best to email me at [email protected]