Horan and co are unbeaten at home in Celtic competition all season and finished 13 points ahead of their Grand Final rivals after 22 Magners League matches.
But despite those impressive statistics, the Ireland front rower believes it is Heineken Cup Finalists Leinster who are currently Europe's form side.
"They are the top team at the moment," Horan told The Irish Times.
"Their defence is fantastic and they are playing good rugby.
"If they do come down here as European Champions it's a great way of gauging ourselves as to where we're at after the disappointment of falling out of that competition.
"We'll enjoy the win over the Ospreys and what it is, but we'll start preparing for the Grand Final.
"It will be another big occasion at Thomond Park, but we've got to come out fighting the way we did in the semi, and maybe with a bit more."
Munster booked the Grand Final showdown with their bitter rivals thanks to a hard-fought defeat of reigning Magners League Champions the Ospreys on Saturday night.
Paul O'Connell and co ran out 18-11 winners against an Ospreys side who had triumphed at Thomond Park last season on their way to a third Magners League crown.
Although the scoreline was tighter than Munster would have liked, the Irish outfit were the better side throughout, with Horan praising his team's mental attitude after a couple of disappointing performances in recent weeks.
"The previous games in the season we struggled a bit. But I don't think those games reflected the work we have done," added Horan, presumably looking back to the Amlin Challenge Cup exit to Harlequins and a 22-6 win over Connacht in Round 22.
"A lot of it was upstairs. I think we're well capable of taking on teams like the Ospreys.
"Mainly it is upstairs in our heads. But our heads were right. I think you could see that right across the field.
"We took them on in the forwards right from the start, and that was reflected in the scrums as well."
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