Tone

IMO (35 years doing higher end car audio) you won't need an alternator or an extra battery if you're only adding a small (or for that matter even a medium or large amp). If you plan to add an extra large amp or amps (say totaling 1000 true watts RMS) then you would be best off just adding a second battery and big 3, and forget about the alternator upgrade. I always add the big 3 too, and run heavy gauge power and ground wires. With one battery, if your dash lights dim a lot when pushing your sub(s) hard then you'll likely need to add the second battery to remedy the situation.

That is an iBoard - they come in all black too.

Just put these Sierra style 20" wheels with 285/50/R20 Blizzaks for the winter on my iridescent pearl 2017 Silverado Z71 with stock suspension. Plans are to put 305/50/R20 tires on in the spring and hope they don't rub. Offset on these wheels is +31.

Okay here is my contribution - I had that same goose groan rubbing sound and feeling that seemed to come from right behind the steering wheel in my 05 Z71 Crew 5.3L with 165,000km. Here's what didn't help - greasing the ISS/replacing the column bearing with a green one/taking apart the steering wheeling and shooting white grease into the top bearing area/replacing the power steering fluid... although the last one cured most of the power steering pump squealing it had. I even ordered a new ISS yesterday as the next step; however, today at noon I had the local Minute Lube guys lube up everything in the front end - immediately afterwards I noticed that the dreaded goose groan moan rubbing was gone. I tried to get it back but can't, I let it sit for hours and tried again when it was cool - still can't get it to do it one little bit! Get out your grease guns fellas!!