hi i fitted the 2.5 na or 15j into my s3 lwb
i used the standard manifold from this engine, which ment that i had to also use it's flange. i had to cut the exhaust and fit the flange then weld it up again.
i used a standard series diesel downpipe, and a deisel backbox
i'm led to belive that a 2 1/4 manifold will bolt straight on to save me having to do it again.
this i have to try