From memory they're about 300cc....not big at all, as some zed people are using the R34 Blue 370's as upgrades.
I've been more than happy with the deatschwerks injectors, I've got the obsolete 550's the newer 600's replaced them on their site last year, they're 100% drop-ins
I remember asking the question about the XR6T injectors a while back, never actually found out though