As for BEF, something funny - My buddy of 2013 335i AWD PWG on PS2+meth+PI, broke 1/4 mile record in early 2017 at Fast4Ward, the biggest drag racing event national wide in China. His time was 11.11@125mph, which is still the second best all time N55 record.
The BEF he used is BM3 OTS STG2 of late 2016, a very early version that's not remotely perfect, and the funny part is he didn't even bother flash newer versions since then... Yet he has the perfect log.
What I'm trying to get at is you don't need a perfect BEF to perfectly push that hard. On the other hand, not pushing hard, flash alone can meet your goal
Good luck with meth with BMS!