Mrad , welcome to the forum. I see no reason to inject a Bird at all(leaves holes for goodness to escape-IMHO). Use JJ's Brine and dispense of the used Brine,it's a minimal cost so no loss.
I did a 14# Bird on Sunday and used Salt , Br. Sugar and some Onion/Garlic for extra flavor. Now if you want more flavor , do as I did and rub a "Compound" Butter (spices mixed with Butter and rolled in wax paper and cooled for cutting).
After 18hrs. in the Brine , I completely dried the outside and under the skin(careful not to tear the skin) and in the cavity. I then cut Quarter sized pieces of the Butter and placed them under the Breast skin and as far down the Legs and Thighs as I could-also on the back. I then Buttered(with same Butter) the outside of the Bird and dusted with my Rub. Placed it in my smoker and let her go to Temp.(165* in deep Breast and 175* in thighs. Then I double wrapped in foil and into the Fridge until Tues.-re-heated at 200* until 165* again , and served.
Was a wonderful flavor and "NO" pockets of over Saltiness or streaks in the meat-that's disgusting looking in my opinion.
Do a nice Giblet Gravy and you've got a "Winner - Dinner"
A lot of people do injections , but I'm not one to defile my Meat , not when the flavor is there , and it's juicier too. I Swear by Brining , as many more on here do...
Have fun and...