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Flat Foot Shifting (FFS) in Action

By Lance Lucas

I was tuning a Stage2+SF+EWG 2013 STi tonight and as part of my normal process, I run the car through a few gears at WOT when I'm all finished to look at things like AFR and boost recovery after a shift.
On this particular car, I did back-to-back 3rd-4th gear rips first using a traditional hard and fast shift, and then again using COBB FFS.  No tuning changes or otherwise have been made, simply disconnected after doing the first run, set FFS to 5500 RPM on the AP and went again.

The attached graph is what boost looks like under the two different conditions.  Using FFS, boost never falls below ~10.5psi on the shift; on a regular shift, boost falls down to essentially full vacuum (-9psi). 

The gist?  COBB FFS flat out works.  Shifting with the throttle plate fully open allows for boost to be kept "up" and recover nearly instantaneously after engaging the next gear.  This is as close to a DCT-style shift as any manual car will ever get.  Badass stuff here folks.

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