Re: Gasket ?'s
I always like to fit gaskets on mating flanges. I know GM didn't fit them to head side or Turbo side exhaust manifolds, but that is when everything is new and flat. When exhaust components heat cycle over extended periods of time things change and parts sometimes warp. You only have to look at exhaust manifolds that have been in service for a number of years, you often need to use spreaders or heat it up to get them on/off. Unless you resurface the faces to like new condition, I think I would be tempted to fit a gasket or Hi-temp silicone as suggested. Not sure if Hi-temp is red or gold, cant remember off hand. Gaskets are available from many sources (plenty for a T3 on ebay for example) Just get a good quality one made from premium material. I'm not speaking from great turbo or SyTy experience here, but from general industry (Nuclear in my case) leaks aren't generally tollerated. In a perfect world, two perfectly flat and lapped flanges bolted together properly 'shouldn't' leak. But unfortunately most of us don't operate in a perfect world and also don't like to do things twice if it leaks. The flip side is that a gasket is the weak link in any joint. I think I would be tempted to go for a thin embossed shim type gasket. I'm sure there are many who have fitted no gasket and have never had a leak though. Weigh up the condition and flatness of the mating faces before deciding.
