I have a 2015 Yukon SLE with the Bose system WITHOUT the sub. I'm satisfied with everything except the lack of sub. What are my options to upgrade as a DYI instead of paying the dealer or trusting someone else to perform this upgrade? I'm pretty handy here but don't want to reinvent the wheel if someone else has already tackled it. Would prefer to stick with stock Bose equipment rather than dealing with a bunch of interface issues in the future. Any advice is appreciated! Thanks all!