Out of curiousity, was it a water cooled CHRA? I'm asking because I'm still trying to get my head around the thermal dynamic benefit of the different thermal management methodologies with regards to their associate cost-benefit.

Yes, ball bearing 1.15 P trim gt35R.

i bought the t04z ball bearing turbo kit from rx7store and i been runnig it for 3 years never had a problem. idk about thr casting but its all good.

my turbo was definately water cooled. here has been some serious heat in the exhaust housing. I also pulled my manifold off and there appears to be more discolouring of the rear wastegate (I run two) suggesting more heat came from rear rotor.
Also the manifold showed carbon/soot in the small hole below the main exhaust port on the rear rotor, but not the front.
What significance is this if any?

all flange faces were pretty flat too but iether way its been machined for more clearance and will hopfully last a couple of months then will be replaced with a BW 9180.