I did a lot of testing on this subject an gained like a .1 on the DMM by skipping the terminals. Box tuning is the only thing that really helped me cut down on box rise. If this is a street box only 1.5 is good. Good luck.
the box cant be wider dan 18 inches,it cant be more dan 15 inches high,dept cant be more dan 21 inches,im looing 2 go ported by d way What is the inside dimensions of the your trunk?