No you don't the battery has no effect on your exhaust. Diy is not needed the install is straight forwrad. If the shop needs a diy for this then they are probably in the wrong business.
You can detect right away those that are going to be shaky, and that will fall behind and those that are very hungry, and that hunger you will have to develop. You gotta create a goal for yourself whatever that may be, a short term goal and a long term goal and you gotta go after that. And if you donít see it, and if you donít believe it, who else will?