Brother when you try a new brand for the first time and mostly a super potent mix like big and full you should do a very small shoot like half ml and on the safest place you can shoot like glutes , NOT THE LEG ( you are asking for pain).
Remember the higher the concentration on product the more pain you suffer . if you cant handle a normal 250mg per ml why buy products with 400 or 500mg per ml?
Even Testoviron from Bayer gives pain for some days and is pharma grade