I offered my FYI to help in selecting a broadhead weight. Regardless of the starting weight, we always reduce the weight further through sharpening. If you want to end up with 145 grain heads, might be best to start with the 160s. And, Rick makes a good point about the heavier steel in the 160s.
I should also note that it's not at all uncommon for broadheads to not exactly weigh the stated amount. Most brands that I've tried have varied by 5 grains plus or minus, some even more. A difference of plus or minus 5 grains or so is minor, less than we take off in sharpening, and not enough that most us us could tell the difference in shooting.
In fact, if we didn't have these new fangled and inexpensive electronic scales, most of us would be none the wiser. Didn't mean to split hairs here. I'll be shooting the 160 STOS until I can buy their 180-200 grain left-wing single bevels when they become available.