X-pipe vs. H-pipe

ok here is an article from mopar muscle.....http://www.moparmusclemagazine.com/...01_dodge_challenger_x_pipe_exhaust/index.html

" Sure enough, the X-pipe produced an improvement in horsepower and torque with a quieter exhaust tone. The peak horsepower with the X-pipe was 466 at 5,400 rpm, while the torque rose to 487 at 4,400 rpm. That's an increase of 12 hp and 15 lb-ft of torque over the H-pipe. We call that substantial. The horsepower and torque reached peak a lot quicker than with the H-pipe, and maintained it throughout the rpm range"