So I told you that I logged some WOT runs over the weekend (saw boost in the 15.5 psi range). The other thing I noticed was that injector duty cycle was up in the 90% range (as high as 94%) at some points. Again, this is a totally stock STI. When/if I swap the DP and get a Protune or Ecutek later on, will I have to upgrade the fuel system? I was under the impression that with minor exhaust mods and some tuning, this would not be necessary. But 94% on stock tune seems like not a lotta room there. Slap me if this is a total newb question, but just trying to learn more about my car. Thanks.
No, you should be good. When you get tuned, they will be able to reduce the IDC to run a lower %. You shouldn't have to upgrade the fuel system until you go with an aftermarket Turbo.
IDCs in the low-mid 90s should be fine... i believe the max duty cycle goes over 100% when the spray patterns overlap... most TBE+tune STis can stay with the stock fuel pump but i know of some people who have had to upgrade to the walbro 255
Don't forget that the stock STi runs pig rich so you'll see lower IDCs just from getting into a more reasonable a/f ratio...
he's right we run real rich from the factory to prevent pinging! The older STI's used to have this slight problem so Subaru compensated by upping the fuel pressure.