As stated by others, it's highly unlikely. I've used 25C intramuscularly a few times, which I assume is in at least the 80s for BA (though there's a lot of variability in BA by IM injection across drugs based on chemical properties, so this is just a guess). In any case, it didn't strike me as much stronger than liquid insufflation. Most find low volume liquid insufflation far stronger than dry insufflation, FYI, but that may owe a lot to the faster rate of onset, IDK. I'm sure somebody out there has used IV and can make a better guess.
I don't really see why anybody wouldn't just liquid insufflate 25C or 25I, though (might be better reasons for other nbomes). You can easily fit 1 mg or more of either in 0.2 mL, cut the very end off a syring cap to form an open protective sheath for the needle and fire 0.1 mL in each nostril (don't even need to snort or tip your head). It's the perfect volume with no drip/no burn/no congestion, and the amount of material used is so cheap any savings from using more potent ROAs is not appreciable IMO. Unlike with most drugs there's almost no drawbacks to insufflation, and of course it's less prep work than plugging IMing, or IVing, is safer than the latter two of those, and sublingual/buccal comparatively seems like a crap shoot for getting predictable effects ...
Is that a typo? You wrote three zeroes, which would be three thousand micrograms = three milligrams. That would be a risky dose of 25I, even if you're doing it on blotter. General consensus around here is anything above 1.5 to 2 milligrams is dangerous and can result in seizures, a trip to the hospital, or death.
3 mg is quite high, but tolerance to nbomes is amazingly strong. For me, 1 mg of 25C is a solid trip, but one day after tripping for a few hours off of 1 mg I just kept adding more and more via liquid insufflation. I got up to a cumulative 3.5 mg over ~6 hrs and still never tripped as hard as off that first mg without tolerance. How strong and how long tolerance lasts varies between users, but even among the non-tolerant some need 2 or 3 mg for a solid trip. It's impossible to know where a newbie is on the scale without starting at a couple hundred ug and working up, and even then because of rapid tolerance development they're possibly contending with weeks or months of titration to get a good feel for their preferred non-tolerant dose.