Originally Posted by 156_TSpark_Boy
I've never understood the pre-cat, is it in the manifold or just after it?
They are two, in the manifold, just after the place where 4 pipes join into 2. Only the 105BHP 147 has a single pre-cat as it has 4-1 manifold instead of 4-2-1.
Pre-cats are there to lower the emissions in the initial period after a cold start as they heat-up much faster to operating temperature being so close to the engine.