finding mistakes or omissions in haynes is great, now you have an excuse to contact them and complain. i've been doing it for years, sometimes you're wrong and they give you a right sarcy email back, but most of the time they're pleased to get the info. tell them, or tell me whats wrong and i'll tell them.
the maxpower modder's guides are very probably wrong, they were written by kids for kids.
you say they dont seem to realise there is a 1.2 spi and a 1.2 mpi, how do you know they dont relaise, maybe they only used the more common of the two in the manual. if you read it should tell you which model(s) are included. it doesnt mean they arent aware of them. the bravo/a haynes doesnt include the hgt but i'm sure they know there was an hgt, just not enough of them were sold to justify its inclusion.