Before the Roe Supercharger, with smooth tubes & filters, headers, & cat back, I found +12/-20 to be the settings I would set it at the most.
I haven't had enough time with it on the road with the Roe Supercharger and the MSD boost retard box, but for the 5 miles I got to drive it before I came across snow & ice sticking to the pavement, I changed the sea level settings as advised by Sean Roe to -8/0 on the VEC1 with the MSD box set at 1 1/2. I suspect that I will be setting the VEC1 even closer to 0/0 later this weekend when A-Vipering I'm A-Going. (Where I live in Ohio is about 850 feet above sea level.)