cliffyk

You don't NEED a custom tune, however even on a dead stock new-edge GT a 93 good octane tune will make quite noticable power gains. I have never used SCT's "canned" tunes, however the Diablo Predator, Delta Force's Special Forces package, and even Granatelli's Fuego can all build good 93 octane tunes.

If you do not care to learn to tune yourself then you may want to wait until you feel you've reached some perceived "tipping point", and have a custom tune done or do a mail-order tune. However you lose a lot of control that way and establish what to me is an annoying and unnecessary dependency.

I have no idea, having never used any of SCT's products or services.

To my mind, as stated above, NO. I am certain there are a number of sources for fully competent mail order tunes, however it is not possible to optimally tune an engine via email--if it were then no one could make money running a dyno shop.

[quote[
4. Am I running lean with exhaust and air mods? If so why can't I just add more fuel a little. I do not have a wideband.[/quote]

No. The intake air (all of it) is still being measured by the MAF and the PCM is adjusting fueling accordingly--there is nothing mechanical you can add or do to an n/a engine, short of very radical cams coupled with optimally selected LT headers, that can affect AFR to any great extent.

You are probably running a bit rich at WOT, by 0.5 to even 1.0 "AFR", as that's what most of the OEM strategies seem to do. As there is no knock sensor on the 2V engine Ford so set them up to go pretty rich at WOT to minimise warranty engine replacement regardless of what kind of swill gasoline was used and how hard it was beat upon. Which BTW is why even a dead stock GT will benefit from a good 93 octane tune.

There is no EPA certification, and therefore no constraints, for WOT operation.