I have a 1999 Johnson 225 HO , what plugs should i use & what gap.  GodBless & Thanks

Plug: QL78YC 

gap: 0.030

Good thing he answered because I would have told you the wrong ones.  I rarely deal with stock motors and I run the 77's, a little colder plug, and that was the first number that popped into my head..

Any certain brand ?  Do they make a marine plug ?

I've been told champion is the only way to go. 

Champion is the only ones I run.  As for marine, the only difference is the marine plugs has a SS base.  I've actually never paid any attention if the ones I get are regular or SS.  They usually get swapped out each year anyway. 

I prefer NGK all day. I run those in everything I own. 

I buy champion but have bought motors with NGK installed and never had an issue with either

20 minutes ago, riverbasser said:

I buy champion but have bought motors with NGK installed and never had an issue with either

It's all preference

if you upgrade power pacs or coils  some of them require different heat range on plug