Great thread. I've been wondering the same thing.
I ONLY have diesels and I've been thinking about a quieter rig for calling. Not only is it noisier than a gas (all things being equal) but my brother's new Toyota FJ is invisible. Coyotes coming right by it to the call!??? Just got me to thinking. My brother says he's never called a coyote while using a diesel rig. This weekend was no exception for him although we've killed quite a few here while using mine. Thursday we were in coyotes using his FJ. Friday we had little action in my '04 PSD.
I also note a difference depending on the amount of traffic the road you're using has. Around here most of the ranchers drive diesels so on travelled roads, I don't think it matters as much as it does in the outbacks.
Anyway, I'm obsessed with killing as many coyotes as I can and I THINK a quieter gas rig might help. Anyone have a good used Tacoma tan in color for sale? /ubbthreads/images/graemlins/wink.gif /ubbthreads/images/graemlins/grin.gif