ok so i am about to do a tune up on my car and i got some HKS spark plugs. Now, when i bought them i only got 2. the heat range is 10, but i dunno if i should put them as leading or trailing.

should i buy another pair of the same heat range and just put them in?

any help is appriciated. thanks!

 

kinda cold unless you are running some major boost.

Normally you would use '7s in the leading and 9's in the trailings