[aaronspeed]

I use E85 in my 725whp Twin Turbo daily driven Mustang and have used a EGT in tuning and it will tell you nothing more than compared to a Wide-band. Why do you think every Dyno uses a wideband and not a EGT to tune. If you put a EGT in every exhaust port and can tune your injectors individually then you have something to tune, but putting a EGT probe in one port or at the down-pipe will tell you nothing without pulling spark plugs. Your better off going the quick and easy route and use your wide-band. I did not post to teach but to give a quick response. I have seen 200 -300 degree difference in each cylinder of my 5.0 and I am sure the way the exhaust ports are made on the 4g63 it would be the same when under boost. Borrow a Thermo Laser temperature gun that goes up to 2000 degrees and point it at the header after you take the car a quick cruise and see the difference between header tubes and then think about the difference when driving under boost. You always tune for the hottest cylinder so why not just use a wide-band since your taking a average reading. Another issue just to mix it up a little, I have seen my E85 range so much that it is like buying 93 octane and getting 89 octane. You always tune for a safe average. It is like tuning with Meth/Water injection and you run out. Either your tuning computer knows what to do or you blow your engine.