Before summer started this year I rebuilt my turbos. In the process I took a 9/32" bit and overbored the four banjo bolt's holes. This will allow coolant to flow through the turbos faster. You can see the size difference in the picture. The two outside bolts are OEM, the two inside are modified.

 

Interesting idea it makes sense but have you seen a difference after doing this?

 

It does look like a good idea to try. Did you take any before/after measurements?

-s-