I've seen different brands of ECA give different ratios. There is 1.5 ounces per 25 pounds and 3 ounces per 25 pounds. The LEM ECA is 3 ounces per 25 pounds, Waltons is 3 to 4 ounces per 25 pounds, Ask the Meatman is 3 ounces per 25 pounds, but Butcher & Packer is 1.5 ounces per 25 pounds. I currently have the Butcher & Packer product and visually it looks like the Waltons & LEM product. I have used the B&P at the "normal" ratio of 3 ounces to 25 pounds and it tastes just like the others do at that ratio. So for me, it is the 3 ounces per 25 pound ratio.
For sticks, I run 3.4 grams of ECA per pound.
Also the twang will mellow after the sticks sit for 24 hours. And if you have never used ECA before, do NOT add it to the meat until right before stuffing and then smoke immediately. DO NOT add it to the mix and let it sit. Also only mix ECA by hand and do not overwork the meat & ECA as you do not want to break open the little fat capsules in the mix. The fat will melt at around 140* and release the ECA into the meat which should be well set by that temp.