I used to have the Banks Monster on a 2005 5.4 Lariat.
It contributed a serious power increase to these underpowered trucks, I'm guessing right around the 25HP the guy on the Banks 1800# said I would get. Problem was, it had an extremely obnoxious drone/resonation anytime while towing & between 50mph-70mph, in other words, right where you would be driving 90% of the time on the hi way. I couldn't live with it and sold it (to a guy who posts here on occasion).
I'm now running the Gibson SI/SO with a 4" tip. Much quieter, not as much power as the Banks, maybe about 15HP. I did pick up about 1.5 MPG with the Gibson as compared to about .5mpg with the Banks. If you're looking for looks & power and noise is not a concern, I would say you should be happy with the Banks. You can get it from AJUSA.COM for $435.
KC-10 FE out...