I have a 04 z250, last week I had a WB E2 slip on put on, and the mechanic said I did not need to rejet unless I was going to run with the airbox cover off. The pipe came with two sets of jets.

My uni filter should be here tomorrow, do I need to rejet after I install this, it just fits in fact airbox and I plan on continuing to run with the airbox lid on?

If so, since I have the jets, is it easy to install them myself or should I pay the shop to do so?

What are the benefits of rejetting?

 

I think you will be fine. Most machines are jetted fat from the factory.
The benefits of jetting is peak horsepower. The expierienced racer messes with jetting depending on altitude,humidity, and temperature.You and I don't care as long as there is no engine damage (too lean).
You "should" be able to change the jets yourself.Some carbs there is a nut cast in the bottom, you remove that and you have access to the main jet. Others you have to remove the bolts to the carburator bowl.
I feel the uni has the same air drag as the stock filter, it just filters better. I recommend Belray Foam filter oil. It comes in a quart bottle and is very thick. NO spray filter oil!
As far as my personnal expierience, we had no jetting issues with similiar mods to the boys 300ex.Pipe/no pipe. Air box lid on or off. Uni/Stock filters.
Hope this helps a lil. [img]i/expressions/face-icon-small-smile.gif[/img]