High Altitude Kit?

Hello,
Just ordered a new Tohatsu 4hp 4 stroke...should be here this week. After making a copy of the owners manual to brush up on the operation of this motor it mentions:

For U.S.A. market only
High altitude:
When engine operates at high altitude engine may have to have a high altitude kit installed. Otherwise, operating the engine at high altitude may increase it's emissions and decrease fuel efficiency and performance.

I'll mainly be useing the motor up around 6,000'. Do you think the kit will be required at that elevation? What does it do, what parts does it consist of, and does it really make much of a differance?
Thanks in advance,
Gary

The kit is for use in the thinner air at high altitudes. It's a re-jet kit for the carb, to allow it to have correct mixture with that thinner air. It should be installed by a mechanic, perhaps your dealer, when he does the PDI on the motor. Yes, it's a very good idea for use above 5,000 feet. That kit will make the carb mixture incorrect at sea level, BTW.