Okay, I know this has been talked about alot but I am still getting conflicting ideas on what I have read on what to do here, Now that I have a tune and want to use a different one, I have installed the 87 performance tune now with a 1/4 tank left to burn off before the 91 race tune install, Now I have read to run the tank down as far as your think it can go the fill up with 91 octane and run it for some miles before installing the tune or just fill it up the 91 right now and install the tune because the Spanish Oak processor will compensate for the octane level and all should be good ??? Can I get a whats best to do here on this , thanks for everyone's help.
__________________
2007 ( Vista Blue ) GT"BUSTER " 2-5-08 See Profile for mods "As I would not be a slave, so I would not be a master. This expresses my idea of democracy. Whatever differs from this, to the extent of the difference, is no democracy." Abraham Lincoln
I'd say just do it the straightforward way... wait till the car's on E (empty) and then go fill up with premium before the tune... that way, it'll always be tuned to that octane and it takes out the variables of compensation
Honestly, if it was a dyno tune then I would wait till it's almost on E then fill up. If it came with your tuner or if you bought an email tune, then you can put 91 in it now. They make the tune as best as possible on what they think with your mods but it's still not an insane 91 tune. It will always be a tad on the safe side unless it's a 91 octane dyno tune.
__________________
1995 Mustang GT-Heavily Modded-Sold 2003 Ford Lightning-Sold 1997 Saleen-5.4 conversion-Sold 2005 Mustang GT-Torch Red-Sold 2003 Mustang Cobra-Oxford White 2003 4Runner V8 Sport Edition 4X4
Honestly, if it was a dyno tune then I would wait till it's almost on E then fill up. If it came with your tuner or if you bought an email tune, then you can put 91 in it now. They make the tune as best as possible on what they think with your mods but it's still not an insane 91 tune. It will always be a tad on the safe side unless it's a 91 octane dyno tune.
Its a Brenspeed tune, I guess I am not so patient to wait till I can get it to empty. And confused by 2005Gt comment about a dyno tune. I thought Brenspeed was a dyno tune isn't it??
__________________
2007 ( Vista Blue ) GT"BUSTER " 2-5-08 See Profile for mods "As I would not be a slave, so I would not be a master. This expresses my idea of democracy. Whatever differs from this, to the extent of the difference, is no democracy." Abraham Lincoln
Its a Brenspeed tune, I guess I am not so patient to wait till I can get it to empty. And confused by 2005Gt comment about a dyno tune. I thought Brenspeed was a dyno tune isn't it??
Not unless you had your car on the dyno and they tweaked it for your car, its not a dyno tune. They developed the tune with other similar cars on dynos.
I had about 4 gallons of 87 in my tank then topped off with 91 before installing the FRPP 91 tune. So in effect I was running 90 octane. It didn't ping. Then ran though about 1000 miles worth of gas before installing the Tillman 91 tune. I like the road race tune better, but the Performance Tune gets better MPG and seems to have a little bit more torque at low RPMs. Can't wait for their all out tune to show up in my email box. Its been 6 weeks since I was told they would send it.
__________________
2008 manual GT with deluxe trim, FRPP CAI, FRPP GTB Mufflers & 91 Tillman Tune. 3.73 gears, Coast Ultralight Drive-shaft. 18" OEM Polished Bullitts, Webelectric Sequentials, XM built into the Shaker 500. Alarm and Escort 8500.
Octane & your tune 
