If I take off the manifold do I need to replace with a new gasket?

 

you dont say if its the inlet or exhust manifold,

inlet will be fine to refit ,as long as you dont damage them,,,,

exhust should be fine also ,........as long as they are in good condition,ie not rusted or broken,not matter if they,re blackend ....

 

mean't to say inlet manifold gaskets.

subaru are charging roughly £10 each.

anywhere else they are available from?