Here's a tidbit from the upcoming XEDE tuning guide:

Tuning the XEDE

Communicating with the XEDE:
Before any tuning can be done, you must achieve 2-way communication with the XEDE. For this, you will need a laptop computer with a 9-pin serial port. If your computer is only equipped with a USB port, you will need to purchase a USB-to-Serial port adapter from you local computer supply store. Many customers have used such a device with success.
Next, you will need to download the XEDE software from our website. It is called XMAP and it can be downloaded here. Once the file is downloaded to your laptop, it will need to be unzipped and installed. This is easy for anyone proficient with basic Windows operation. If you have any questions, please contact someone who can help you. Once installed, it is now time to start XMAP. A small window will appear on your screen. It is called the Data Monitor screen and it will look like this:




With the serial cable connecting the XEDE to your laptop, you will now need to establish a connection. Turn on the ignition power and start your car. With the engine running, confirm that the indicator light on the top of the XEDE is solid green. With the XEDE now power up and running, it may automatically establish a connection to your laptop. You will know this by all the new activity on the Data Monitor screen. You will also know this by looking at the Status display on the bottom left of the screen. It should now read Connected. If there is no such activity or if the Status display still says Not Connected, click on the communication icon just to the right of the question mark, just below the menu. It looks like two arrows pointing in opposite directions. This should result in successful communication between your XEDE and your laptop. If there is still now connection, confirm that the serial cable is installed corrected in the XEDE and in your laptop. If there is still a problem, there may be a port communication issue with your laptop that you will need to resolve. Another possibility is a faulty communication cable. While both problems are rare, they should still be mentioned. If you continue to have communication problems, try using another computer. This will almost always solve the problem and shed light upon what is going on with your first computer.


Uploading/Downloading maps from the XEDE:
With communication now established between the XEDE and your computer, you can now upload new maps into the XEDE or download the current maps from the XEDE. Unless your XEDE is pre-loaded with the appropriate map, it makes no sense to download the maps from the XEDE.

Understanding Tables:
In all the tables (boost, fuel, spark timing, knock, etc,.) the Y-axis, labeled 0-100% represents engine load and the X-axis represents engine speed (RPM). During cruising and other off-boost conditions, your engine will operate in the lowest load row (Load 10 in this case). In fact, with the engine running, you will see a yellow cursor on each one of the tables. This represents the cell which is currently active. If you blip the throttle or go out for a drive, you will see it move around from cell to cell. Of course, you should use a friend for such antics as you should never take your eyes off the road while driving, right? Another neat feature incorporated into the XEDE software is the ability to select the currently active sell by simply hitting the space bar. This is helpful if things are moving around to fast.
NOTE: As long as the XEDE is operation and on-line (Indicator light is constant green), all the changes made into the XEDE tables are immediately active and will remain stored in volatile memory until the XEDE is powered off (ignition key off). To make the changes permanent (immune to power-off), the maps will need to be burned into the XEDE¡¦s EPROM. For these directions, read this.

Adjusting Boost Pressures:
With the maps currently displayed on your computer screen, you will need to find the boost table. It should look something like this:



The numbers in the table represent the absolute duty cycle of the boost control solenoid. The bigger the number, the greater the bleed of the boost control solenoid. And the greater the bleed, the greater the boost level. Get it? You¡¦ll also notice that the lowest load row reads 100%. This is to keep the solenoid from being active during off-boost conditions which represent 99% of the time. It is recommended that all boost table tuning be isolated to the rows just above the lowest load row. In other words, always keep the lowest row set to 100. Those of you who are already familiar with electronic boost control systems may also be aware that keeping the solenoid open (100% duty cycle) can improve boost response until just before the desired boost is reached. This is another reason that the lowest row is set to 100%.

Now, let¡'s say that you want to reduce peak boost pressures at 4700RPM. Simply reduce the numbers in the 4700RPM column. This is down by selecting the necessary cells with your mouse (remember to the leave the lowest cell at 100%) and clicking the < (LESS than) key. Each click makes a 0.4% change in boost control duty cycle. It is recommended that you make changes to the boost table in 5% increments. This will require several clicks and should result in a discernable change in boost pressures. Once you get close to your desired boost pressure, you an make smaller increment change for fine tuning. Conversely, clicking the > (GREATER than) key will increase boost pressures.

Now, let¡'s say you wanted to make a change to boost pressures at every engine speed. To do this, you will do the same as described above but use the > key. However, instead of selected a single column, you will select all the columns (and like always, leave the bottom row set to 100). You may notice that the more cells that are selected, the slower the table response to clicks of the < or > keys. This is normal so be patient and click slowly for XMAP to keep up.