For me, as a general rule of thumb I leave myself room for growth. right now DSM injector might be enough for you, but down the road you might want to do some upgrades to the engine and run more boost, then the DSMs won't be enough. Also use some common sence when doing stuff like this. You will probably never need 1000cc injectors. IMO I'd rather pay a little more once then go cheap the first time, and get the right thing the second time (right dosen't mean being a brand whore either).