the F-15I is not much different from the F-15E both of them were made by MCDONELL DOUGLAS that doesn't exist any more from the simple reason that it was bought by BOEING and now BOEING is the biggest
Air-Space company in the US and in the world for that matter.
The F-15I was made for the IAF (Israeli Air Force) ,ISRAEL needed
a fighter that will be more compatible with the Israeli weather and conditions and more compatible with the missions that the Israeli
air-force conducted, for that there were added:
 The Hughes APG-70 synthetic aperture radar, The Kaiser holographic
head up display system ,The Elbit display and sight helmet (DASH).
Armament---
 The new "Python 4" was developed by the Israeli air-industry.
The "Python 4" is the newest and has the best kill-to-hit ratio
from all existent air-to-air missiles and ground-to-air missiles.
 The Aim-120 AMRAAM is also one of the weapons that will
be widely used in the F-15I ,this missile was improdused some
months ago to the IAF.
Besides the new weapons the F15I has a bigger fuel tank and has
improved engines.
Engines ---
          The F-15I has two Pratt&Whitney F100-PW-229 power plants
          those engines are much more powerful than the engines
          of the original F-15E.

History ---
          The F-15I aircraft first flew on september 12 1997 at that flight
          the plane reached Mach 2(Mach=1,224 km/h at sea level)
 
The first two F-15Is are scheduled to be delivered in January 1998