I would think 108% volumetric efficiency (VE) may be a little low for a turbo car. Basically if this is true VE it means you are filling the cylinders to 108% of maximum capacity. It is telling you that if your cylinder can hold 1 pound of air/fuel you are really putting in 1.08 pounds due to the efficiency of your combination. That is what a supercharger or turbo is suppose to do right? I would think you would do better than that though. I have cells in the 105% - 108% VE range at wide open and I am naturally aspirated. My VE tables coordinate with actual dyno VE results so I think I have all the parameters in the software correct. Having VE numbers above 100 is not unusual with high performance engines. Not ever running a supercharger or turbo or seeing one on the dyno I have no idea what yours should really be at.
Although I have not had to do it, if your base tune up is fine and you switched injectors and changed your injector size in the computer it should compensate your pulse widths of the ijnjectors to maintain A/F's.
VE numbers, injector size and HP have nothing to do with each other. What it does sound like is your injectors are too small if you have a 98% duty cycle. It sounds that simple. Another option would be to increase your fuel pressure or make sue you are maintaining fuel pressure first. That would lower your duty cycle.
Although I have not had to do it, if your base tune up is fine and you switched injectors and changed your injector size in the computer it should compensate your pulse widths of the ijnjectors to maintain A/F's.
VE numbers, injector size and HP have nothing to do with each other. What it does sound like is your injectors are too small if you have a 98% duty cycle. It sounds that simple. Another option would be to increase your fuel pressure or make sue you are maintaining fuel pressure first. That would lower your duty cycle.