New bike no Exup

[PieEater]

So the bush should just slide into the headers, shouldn't be a tight fit as standard?

As b1k3rdude said grease the inside and outside of the internal bush with copper grease so it sticks on the spindle and it will slide into housing with no force required. It helps if you shine a torch into the exup port so you have a visual image of where you need to insert the spindle.