[seningen]

If the fuel injectors have 30% margin in them you can (I don't know)
then add a pulse width stretcher to the FI wiring harness,

We have converted a 924S NA race car to run E85. We did not notice and appreciable
increase in fuel consumption. In our case the 944 Turbo injectors flow 28% greater and we just swapped them in and fired her up.
Checked with a wego and all was good.

Butt dyno says we're doing fine on power. Smells weird -- not bad just weird.

Only issue we had was we needed to replace the fuel filter when we ran out of gas.
Gummed up from sucking up the bottom of the tank.

FWIW, we ran out of fuel because our gauges lost a ground connection
and it was coincidence the fuel gauge stopped recording properly (read 1/2 tank).

Note this was only our first race -- but 22 hours on the clock -- so far so good.

There are concerns about fuel lines, pumps and filters -- but the jury is out on this.

Last ethanol we bought was $2.99/gallon and with the Boxster's needing premium
thats > $1.00/gallon cheaper.

I've considered converting my Boxster S, but haven't done so yet.
Mostly because the Ethanol isn't conveniently available.

Mike