What can we measure

[Steve Baldwin]

My post of the other day was intended to spark discussion of what
alternative sensors are available that might be utilised in a small
volume EFI system.
For example. Exhaust temperature varies with mixture. Leaner being
hotter. Can this be utilised for feedback ?
MAS sensors are more expensive than MAF, but are a direct measurement.
What alternative methods are there for measuring mass other than the
constant temp hot-wire anenometer ?

Any lateral thinkers out there ?

PS. I'll be using leaded gas because that's what they sell around here.
We have 96 octane leaded and a 91 octane "unleaded" that still has too
much lead for catalytic converters.
Incidently, there was an unleaded "unleaded" sold here for a while and
it burnt my (and a lot of other people's) valves out real quick before
it was withdrawn from the market. I don't know if the unleaded vs. valve
life issue was a farce or not in the US but I'll admit to being a bit
shy of unleaded gas for a while. 

Steve.