If you got them from M'B, the adhesive is strong enough. Just take care not to contaminate the surface after the backing is peeled away.

When I install those letter badgings, I always leave the letters as they are on the package and cover the entire chrome portion of the letters(non sticky side) with a strip of duct tape so all I have to do is peel every letter from the package while it is still held perfectly in place by the duct tape, then I place it on the car where I marked an measured the correct spot.

After I stick the letters on and am satisfied of placement, I then remove the duct tape and all the letters are without question, spaced as they should be.