How can you get a new air filter in the same box?No, the FPP includes a new filter, but no changes to the filter box or air tubing.
The total gain may be higher than the 15hp from Roush, or may be the same. Would love to see a real dyno comparison of the two options.
Both options seem to have VERY modest gains at a fairly high price, but do protect the warranty.
The new filter is supposed to have 22% more air flow...I would guess that to mean more surface area.
The muffler has a one inch restriction to dampen noise. The cat back opens these pipes as well as removes that restriction. I see that as an improvement. Why would I pay for a new filter and expect increased performance?
I suspect you can do better with performance by not investing in Ford's "copied" package.