Are you sure? from what I remember the original F-15S were downgraded and that was one of the primary reasons the RSAF opted for typhoons : Paint Scheme: The most apparent difference between the S and E models is their paint scheme. The E model has a one tone gunship grey color, while the S model uses a two-tone 'Mod Eagle' paint scheme.
Engines: The F-15S is equipped with Pratt&Whitney F100-PW-229 engines, the stronger one from the two P&W engine models used in the Strike Eagles.
Its radar, the APG-70S is based on the APG-70 radar of the Strike Eagle, but with its main features significantly downgraded. Radar bandwidth is 60% of the 'original' and only 16 channels are available instead of 32. Although the APG-70S has SAR capabilities, the ground mapping resolution is severely limited: the minimal size of the HRM the radar is able to generate is 4,7 nm, compared to the 0,67 nm of the APG-70.
Navigation and Targeting Pods: LANTIRN pods are also degraded. Instead os using the 'standard' AAQ-13 navigation pod and AAQ-14 targeting pod, Saudi Arabia received 48 pairs of AAQ-19 'Pathfinder' navigation pods and AAQ-20 'Sharpshooter' targeting pods (use their original designation number and add 6 to them). The navigation pod is downgraded in its ECM modes (it works reasonably well against potential russian-made Iraqi and Iranian threats, but performs poorly against US aircraft) and it has no ECCM mode. The AAQ-20 targeting pod has basically the same features as the AAQ-14, with the exception of being incompatible with AGM-65's hands-off modes and lacking some of the A/A features of the LANTIRN targeting pod.
Avionics: The S model's autopilot lacks the terrain following capability which is present in the E model. Its navigation system is a laser ring gyro INS coupled with a commercial-grade GPS system - although it works well, it is definitely not as precise as military-grade systems.
Weapons: The United States took great care in the area of weapons. The F-15S cannot employ the wide range of weapons the Strike Eagle can: AGM-65D/G Maverick missiles, CBU-87 cluster bombs, GBU-10, GBU-15 and GBU-24 smart bombs belong to the inventory of the Saudi version. Understandably, the F-15S does not have the wiring to be able to employ nuclear weapons. BRU-46/A and BRU-47/A weapon racks were initially lacking from F-15S delivered to Saudi Arabia, but this restriction was cleared later and 'normal' CFT's were delivered between 1998 and 2000.
Don't get me wrong they are still formidable aircraft and for most advesaries should be enough - however the USA still finds a way to protect Israel's interests and will never supply Gulf states equipment that will jeopardize it's Jewish ally.
