What I don't get is people leaving 25 or more HP at peak and even 5 ft# of torque across the rev range on the table. That's not efficiency. Just because you don't want to deal with headers. Many headers now days fit, most don't leak when properly installed and some fit without modification. BUT WHEN EVERYTHTING IS CUSTOM, ALL ABSOLUTS OR LIKELYIES ARE OFF!!!! If manufacturers could justify long tube header price, pass NVH issues, install complications, guarantee they would last past the EPA mandate of 100,000 miles and would be trouble free' "no warranty issues". THEY WOULD USE THEM. The power and mileage would be up, EFFICIENCY would be up!! That's why we hot rodders use them!!! They make POWER!! Mileage "efficiency" is a bonus..
