You need to watch your compression. If you have Cudney's head call Bill, he's a flat lander. His heads are typically not as aggressive as RKTEK's. You might be able to get by on Premium. The RKTEK domes I run at 9-12k feet I would not run at 1800 feet. I would swap them out. If you don't like to turn the wrenches you should find the most aggressive head you can run at your lowest riding altitude and leave it alone.I've got a Cudney head on my summit with the regular trail domes. I was wondering if it anyone switches them out for the high altitude domes when they ride the mountains? I don't remember where I checked, but I think i was told it was around $150 for an extra set. I'm sure they help, but is it a big enough difference to justify spending the money on them? Also, Does anyone know what kind of octane I'd have to run to use the mountain domes at 1500-1800 ft?