When the Raptor finds itself in a dogfight, it is no longer beyond visual range, but the advantage of stealth isn't diminished. It maintains "high ground" even at close range.

"I can't see the [expletive deleted] thing," said RAAF Squadron Leader Stephen Chappell, exchange F-15 pilot in the 65th Aggressor Squadron. "It won't let me put a weapons system on it, even when I can see it visually through the canopy. [Flying against the F-22] annoys the hell out of me."

Source: http://www.acc.af.mil/news/story.asp?id=123041831

So does this mean the F-22A's IR-suppression is far greater than we thought?

Outside of the F-15C's AIM-9s, does it also have an IRST system?

Possibly. The technology/materials/coatings certainly do truly exist for.... how to say this... "Phase Shifting" an IR emission. Essentially if the materials used on the 'cans' are certain materials/coatings, then they may not register on an IR seeker tuned to specific wavelengths, especially if you're a mile or more away... If certain technologies were used, then indeed its possible that the only way to get an IR "lock" would be if your IR seeker is pointed straight into the exhuast can and looking at the red hot glowing emissions.... Now, in afterburner, you can't do too much about that because you're got 20 foot or there abouts flame sticking out of your a$$. Thats where the F-22 beats the F-35 hands down... flying supersonicially undetecably (or at least with greatly reduced ranges as aint nothing in the world undetectable by any stretch of one's imagination).