They are available, Holley makes some, there's a TBI injection system out there, look to spend $1500-2500. That said you a barking up a tall tree. I am servicing both carb. & TBI-EFI systems & both are calibrated for the specific engine, setting up an EFI takes alot of mapping in the ECM to get it to perform correctly. My sources tell me that the older american made Holleys are far superior to the currently available Holleys that seem to be more prone to failures from todays gasolines. My advice is to tune what you have, the biggest advantage in our ski boats to EFI is the cold start running, after that there's minimal advantages.