Thanks Ron for your clarification, perfect timing!
I found the 1/8" Acid core solder today at Pep Boys ($9something per roll) in the electrical section. I also picked up a smaller diameter roll of Rosin core since someone said the 1/8 was too big.
Well, my '10 ec300 barely kissed the .125 solder, I measured around .112 to .116 at the ends. From what I've been reading, if the measurements are taken the same way, it boosts my hopes for large improvement even more.
FYI, I also checked Home Depot, the one by me only carries the lead free solid wire style.
I'll be sending my head/carb/slide to RB Designs in the morning! Updates to follow.