Has anyone seen a difference between using the screaming eagle and standard OE spark plugs?
Is it worth the extra money?
Any performance improvement?

It looks like the SE plugs are iridium plugs which I always use in my cars / trucks.

 

I've used both. No noticeable difference. Some say the SE version burns hotter thus contributing to heat, but I have seen no data to support that assertion.

 

I have always used the stock plugs with good results. I did try a different plug once but didn't notice and difference so I switched back to stock plugs.

 

I use the H-D double platinum plugs for one reason, they last much longer.

 

I've been using NGK Iridiums.

 

i stick with the stock hd plugs for one reason. the ecm requires your spark plugs to be a certain ohm rating in order for the knock sensor to work properly. other plugs may fit, and they may or may not have the correct resistance. i know the stock hd plugs do. it isn't like you have to change them with every oil change anyway so to spend a couple extra bucks on the hd badge is no big deal.....

 

I used both on my fxst and nvr noticed any difference

 

Is the knock sensor different from automotive? Not a pezio electric knock sensor?

 

i use the v-rod plugs in my 12 CVO. They are a colder plug and it reduces the tendency of the 110 to ping under load. Replace every 20K.

in my 04 which is a 107, i run autolite plugs from the local auto parts store. they are about a $1.50 and i replace them every 10K.

The 04 tends to be more tolerant of non HD plugs than the 110.

 

No, I do not believe there is an "knock sensor". I'm knot sure how the system senses knock?