It depends on several factors.
 

1. You can work with the same mold, but you need to consider what happening with the cavity surface, due to a great friction inside if try a 50% of G.F., your mold must be have a surface treatments, or special finishing protection, also some time is better use special oil.
2. If the sink marks is continuously you can try to improve some special test runs into the injection molding machine process, I recommend you try with 3-4 different profiles at the second pressure in order to led the flow front advance and fill the cavities more properly.
3. The data of the material that you are using is around of: Linear mold shrink for PA66+30GF 0.2-0.6%
   Melt temperature 428-579 °F
   Mold temp. 104-140°F
   Linear mold shrink for PA66+50GF 0.09-0.11%
   Melt temperature 455-590 °F
   Mold temp. 104-140°F

It is bit unfortunate that the injection molding machines have made so many advances whilst the mold- where all the action happens remains in 17th century- apart from using CNC technology that makes it more accurate reproduction of CAD file. Cooling is by and large after thought, where can I put some cooling lines? Radiator in a car is not an option, car will not run without one and why our molds have an afterthought for radiator? How many tool specifications define no. of shots to tool stabilization? Uniformity of temperature over entire part (just take a simple thermal image of any part after injection molding and see how bad the variation is). Parts vary in quality and have warpage not so much because melt is having some variation in couple of degrees C, when tool has hot spots and delta T in excess of 60 Deg. C.