K&N Performance Air Filter Kits

I was wondering what the difference between the FIPK eries 57) kit and the "Performance" Series 77 kit was, other than the 77 kit being chrome instead of plastic. My assumption was the new 77 was supposed to be higher performance as well, but I was wrong.

According to the K&N website, the series 57 kits gives an extra 10.49 horsepower for the 5.7L HEMI, while the 77 only gives 8.34 HP (dyno chart), and the 57 seems to be more consistent boost across the RPM range.

FIPK Installation Instructions for 5.7L HEMI V8.