I recently completed removal and replacement of the cylinder head on my 97 V90 due to 17 bent valves after a timing belt failure at 70 mph caused by a seized idler. What a job it was, a few hitches here and there but it's complete and engine is running great.
During the course of the job 2 questions came up that have me very curious.

1.
The pulsed air injection system whose purpose is to flow air into the exhaust system for a minute or so on cold start ups feeds into a passageway on the top of the upper head under the plastic coil cover. How does this passage feed into the exhaust?

2.
There was no rear camshaft seal installed at the rear of the intake cam when I disassembled. Upon talking to a seasoned Volvo indy mechanic he said that he seemed to remember the same thing. I did not install a seal even though the head and upper head are machined to accept a seal. Of course I did install a new seal on the rear of the exhaust camshaft as well as 2 seals on the front. There is only a push in plastic dust cover over the opening where the "missing" seal would be. There was no sign of any oil leakage before or after the job. I thought this strange.

Any thoughts????