does putting an au manifold on an ef xr8 make much difference. is it worth doing? and if it is is there any other thing i should change when i put it on ?

Yes, if you install an Explorer manifold and matching TB then you will gain some extra horsepower. It won't be a lot but you will most likely notice it in a seat-of-the-pants way.

if you get some head work done at the same time things will start to look up... the manifold fows better, but you need heads, ehaust to get the best