When you get the chance take a peak at this:


http://www.innovv.com/the-k

I have it and it is well worth the money, both front and back cameras with loop recording.
The pipes won't help you with the people in front of you who will change lanes w/o signalling because that sound is being sent in the opposite direction the only other thing that will help this for a fact, because I have that installed also is:

https://kisantech.com/mag/pfin.html

The GoPro is good, I would mount it on the front, better than nothing but if you can swing the above you will increase your visibility and surveillance by 10 fold. Don't forget these days the cars are extremely soundproof and with the music blasting and AC on they're not hearing pipes sending sound in the opposite direction they WILL see you with flashing headlights coming up on them in their rear and side view mirrors.