99 40 hp johnson mods

[Xpress2830]

I think by the time you get he 50hp head and plug your idle relief hole your compression will be high enough I'm not sure you'll be able to go any higher on 87 pump gas.

Hey rude the only holes this head has is the water jacketAttachment 59160

[Lil' Blue Rude]

The idle relief holes are in the cylinder wall above the exhaust ports.