I currently have a 2014 Ford Mustang V6 Premium. When it comes to exhaust I have roush axle backs currently. What I want to do is replace my stock headers with BBK long tube headers and BBK midpipe with high flow catalytic converters. As far as sound/performance what gains can I expect? I do want it to be a mixture of a little louder and little more HP. Also, I do want to tune my car, but should I wait until I have those parts on the car to keep from having to re tune it?