Well I installed the system this morning, Ford racing sport system ( resonator delete) . 2 people 1 hour 15 minutes, so easy it makes your head spin. Really easy on a lift. If you have a lift it's really helpful.
I drove it for about 35 miles in town and on the highway, it does have a healthy drone from 1800-1950 rpm under a load, like an uphill . But that's only at highway speeds of 65- just under 70 mph in 6 th gear. If you pick up the speed to 70 and 2000 rpm it's gone.
So I MAY put the stock resonator in line after a while of driving if it bugs.
But it sounds great at start up, and when you get into the throttle, it sounds gnarly! Deep and classy like NASCAR .5000 rpm 3/4 throttle is awesome!
Truck feels a bit peppier but can't really notice any sig. Increase, but it does breath easier, that you can feel.
Here are some pics, and I'll get a sound byte in a while..
Overall I like it. 49 state legal.