I was just told that our sc injectors that we call 30 lbs are not 30 lbs but infact 28.55 i have many sets from 89-93 and they have a 0280150945 part number which is 28.55 lbs not 30 and was told red tops vary from 28-32 lbs why do we refer to our red tops as 30 lbs and why do we refer to the 94-85s as 36 lbs when they are 34 lbs