Thanks for the reply.
This is my first M54 but not my first headgasket or engine rebuild.
I've used TTY bolts on the last M20 projects where they replaced the old style.
My plan was to get a different set of head bolts and re-do them one at a time and maybe be a bit more generous on the lube in the non-threaded parts of the bolts. I have several torque wrenches of the lower cost variety so I may set them all to the same setting and see if there is much variation.
I can also try calibrating them to see what they actually read.
Does the re-do one at a time make sense since the headgasket has been compressed?

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2001 x5 3.0 (sold with broken motor), 1990 e30 M3, 1991 318is, 2002 325i, 2008 335i Dinan stage 3 6 speed,