I have the second edition. In this there is a table 10.11 on page 241 that is called "manifold selection chart". I can't make much sense of the several websites where you can buy exhausts. I have asked my Mini specialist to source the correct exhaust for my to-be-engine, which will be a 1293cc engine with about 80-90bhp. For this engine it should be the medium bore exhaust in LCB style. We'll see with which one he comes up.
I dug up my book, will have a look. Maybe this is a lot of hassle when my standard MG Metro cast iron manifold with Maniflow downpipes delivers the goods. But cast iron is not very goodlooking.
Just got a mail from Maniflow, they seem to work on sunday evenings! I was recomended the LM021A manifold. Can´t find any info about that manifold though only LM021. Has anyone tried the LM021A?