Heater core replacement

[Matt Bolles]

When I replaced the heater core in my car, I replaced the silicone material surrounding the two hose outlets with a Permatex brand black silicone, unfortunately, not giving it too much thought.  When I turned on the heat for the first time after the job was complete, a burnt plastic-like smell filled the cabin.  I thought that this was something to do with the new heater core; I was wrong.  Thinking it would "burn off" so to speak, I left the heat on for half an hour the next day on my way to work, before I turned it off as I was starting to get a headache.  I am fairly certain this has something to do with the silicone that I used, as it gets hot from the coolant flowing through the core, it emits this awful, almost toxic smell.  Has anyone made this mistake also?  I feel incredibly foolish for not considering whether a particular product is called for when replacing the silicone surrounding.  Could there be something else I am not considering?  This smell does not occur when the AC is on, only when the heater is.  I am dreading having to pull the box out again, though, for my poor planning, I think I may deserve it.  Any thoughts would be appreciated.
Also, any thoughts on what to look for in a replacement turbo?  I'm not looking to upgrade, just replace mine with same or similar unit.

Thanks,
Matt Bolles
'91 200 20v-203k
'03 A6 Avant-59k