[DL175]

If you flushed and filled with water to circulated then there will be water inside the block instead of coolant. If you flushed it but did not circulated the water by running the engine then no additional water will be in the block. If you use concentrated coolant you can adjust for what is in the block plus what you add to the system. If you use 50/50 premixed coolant it will be weaker if you flushed and circulated the water.

 

[DL175]

I flushed but did NOT circulate water through it, only used Toyota's premixed 50/50 coolant for the entire process. I'm sure there's still some residue of the previous coolant, but majority is gone and shouldn't have much impact.

That's good.