560 ti SLI question

Quick question. I have an MSI 560 Ti 2GB/OC. Was wondering if I wanted to run SLI with this card, could I get an EVGA 560 Ti (or any other manufacturer)? Or can I get the 448-bit MSI 560 Ti card and SLI with that? I know that you need the same GPU and I'm pretty sure they all use the same GPU but with different settings on them and some have different VRAM (which I know you cannot add the two VRAMs together to get, say, 4GB of VRAM). I don't have the cash to just buy a GTX 670/680 so it's not really an option. I've only had mine for about 9 months.

Any tips are appreciated.