Infiniti g35 oil consumption?

I have completed 2 oil consumption tests through an Infiniti dealer and the car is losing about 3qts of oil ever 1k miles. I have a 2004 g35 coupe automatic. The only modifications to the car are an exhaust system and intake filter. Infiniti has denied replacement of the motor because of my exhaust system (which is bs). What should i do next to resolve this situation?