AFM before or after turbo?

[E30GoDz]

ive seen it done both ways, what are the advantages of each?

[m3k]

Afm are best used before the turbo/supercharger mainly because of the fact that most afm are either hotfilm or hotwire, either way measuring the amount of air- Compressed air should be measured by volume (map sensor) rather than trying to measure the air in compressed form. almost every factory turbo cars use afm's before the compressor. The only good side about the afm in the charge pipe (after the compressor) is that you can use the blowoff to open atmosphere so long as you vent before afm!