2004 GTO turbo install!!
it will be a fun car. for sure. anything with a turbo is bad *** in my book.. !! just needed a bit of neatness to it i think
The only area under pressure is between the pump and rack itself, and this is very very high pressure.
But on a budget it's just a case of hunting down one from another vehicle. Ebay is usually a good place to search.
If it's just an overflow bottle outside of the pressurised system, then the PAS one you have would be fine.
But if it's a reservoir integral to the pressurised system, then it needs to be suitable for that task.
Some cars use none ( any airspace/fill point would be via the radiator itself ), some use one, some use both types.

