I have noticed after a set of my plugs fowl with carbon, my highway and city gas miliage drops significantly!
Normaly, I get 20 mpg highway, im getting 16 mabey right now.
I get 15 city, and get 10-12 right now.

Replacing them puts the numbers back up to normal for a few thousand miles (6k+).

Anyone else notice this?

 

Well it is common sense isnt it? If the tips are fouled they wont nearly spark as well so you waste more gas instead of using it most efficiently right?

 

i dont know if my milages went back to normal...but i def noticed a increase in power

 

Depending on how bad they were, replacing them can yield more power, better fuel economy and a smoother engine all together.

 

If they're not sparking well and not giving you a good burn, then your engine is going to have to compensate by throwing in more gas to get the same acceleration result as if you had good plugs.

 

crap..probably should change my plugs soon again....these things go every 6 month....im planning to run 12psi with rb turbo back and mbc and walbro with 550/750cc rtek1.7....should i be looking into colder range plugs?

 

Maybe look into getting an msd6a?

 

Perhaps one step colder each.

 

I sand blast mine every 4 or 5 months...then blow them off good..they are just like new...also had more power