I have a 8 Valve 1.6 in my sami and the power is good but its getting horrible gas mileage. It has a generic electric fuel pump and the engine is has a carburetor not an injector. Is it possible that it the fuel pressure is too high or does the carb need to be rebuilt? I was also wondering if anyone knows if changing out the valves, springs, and lifters is pretty straight forward or should I have a shop do it? Any help would be appreciated.