The F-15 is and always has been, a semi-stealthy plane. There are certain angles of aspect at which the radar return is greatly diminished. Those aspects were degraded by the extra 'winders on the inboard pylons and three 600 Gallon tanks. The FAST Packs changed that greatly. Moving the AMRAAMs inside a third conformal tank/weapons bay makes it much better. believe it or not, the F-15ES is probably better at LO than either Eurofighter or Rafael. Either of which has so many defects in the EMR Spectrum that neither is very LO at all. I once posted a list of easily visable defects on Rafael that should convince any who were looking of my position. Eurofighter is better, but not really LO.
I still find it amazing that so many here refuse to compare the euro canard-deltas with what is arguably their most significant competitor, the F-16 B50+! Neither is significantly more effective at LO and depending on the mission requirements, fails to meet the range performance. Such as when they have to carry Mk-84s and thus sterilize the inner wing hard points for fuel and thus range.