What's the difference?

How does one know which one to use?

Try this from Pablo's site:

http://pantablo500.tripod.com/id34.html

Which ones would be better for our little GS's? I was told the hotter plug when you add a pipe and rejet, but reading everything, you want a colder plug for higher temps and higher speeds. I run HWY most of the time, bike is air cooled (so the motor is hotter). Or should I just stick with the stock ones?

your bike is liquid cooled...i think normal will be fine...especially temperature over at your area is quite warm

Quoteyour bike is liquid cooled

If your talking about the new oil cooler,  :lol:  :lol:  :lol: .
That thing isn't big enough to be considered liquid cooled.

Run stockers for a week, then check them, if you have any problems then go the way you need to, if not just run the stockers.

ues a cold plug if you ride with hi revs or have geared down your bike.     use a hot plug if you ride at lo revs all the time.    i use a ngk dpr9ea-9    the higher the number the colder the plug is.    i just rejeted and added a full v&h system and a 15t counter shaft sprocket.  so im turning higher revs.  see ya.