Has anyone tried these H4 bulbs?

I have the old style IPF H4 housings and I'm currently running Narva 90 watt low/100 watt high bulb.

Check these out:

http://www.4by4connection.com/ipfh4sulowbe.html

# IPF H4 X51 Fatboy Super Low Beam Huge bulb with exotic high pressure-gas mix delivers more light
# No wiring loom upgrade required
# Filament stabilizer technology for use in harsh conditions
# Fatboy draws 80 watts on low beam, 60 watts on high beam
# Optical equivalent to 190 watt low beam, 150 watt high beam

Would these be a significant improvement over my Narvas?

Yeah, going to be an improvement over the Narvas...however...getting used to the high beam being DIMMER than the low beam is difficult. For a good bulb also consider the PIAA Extreme White (NOT the Super White). I've got those in with the IPF H4 conversion and they are very bright.