I have a pair of Honda EU2200i generators modified for lp or natural gas with the Hutch Mountain kits. As it was nearing time to replace their spark plugs, I thought I'd give the NGK Iridium plugs a try. Shipment from Hutch Mountain was quick. After I installed the new plugs, I was pleased by how quickly they started on propane. On one of the generators, I swapped out the lp orifice for the natural gas one and repeated the test. Again, a quick start from cold. For the record, the old plugs didn't appear worn; I'm confident the iridium spark plugs significantly improved how quickly my EU2200i generators start up.