I had the same decision to make about two years back. I had a gt28r and wanted to upgrade. I went for the gt3076 and really made a bad choice. It worked fine but it was very laggy I had to make 340whp to run the same I did with my gt28r with 300whp because of the loss of powerband and torque. so if your aim isn't 450+whp take the smaller one. or find a gt3071 if the gt2871r isn't enough