CDI boxes

What I think is funny is that most of those bashing conversations go something like this..."RevBoxs suck, they are a POS blah blah blah. I only use Dynatek, they are better"

Dynatek makes about 90% of the CDI boxes on the market. Other companies just slap their sticker on it.

There is nothing wrong with Big Gun.

The CDI is plug and play. The z400 already revs higher than the EX, there for the rev box won't increase a full 1000rpms. Different machines get different gains. They advance the timing which is the main function of replacing the box.

You don't have to change cams, but to see/feel the full potential of a CDI Box's gains you should change cams. Most, if not on all ATV motors the HP output drops the last couple hundred rpm. When you change the cam along with the exhaust and intake you are increasing your HP output so you can effectively use the extra 1000rpms. If you add an extra 1000 rpm's to a stock motor, you will actually lose speed and power at the top of your rev limit. But the advanced timing which leads to better throttle response is more noticeable than your loss of top speed and power.(This is at the very top of your rev limiter, you don't notice any power loss. You will only see it on a dyno machine)

The CDI is not going to be a "oh my god, what a difference" kind of change but your quad will be a bit snappier and have a bit better throttle response. It won't change how your quad runs in each gear. That is all done by sprockets.

You can always go down 1 size on the front sprocket. You will gain more torque/acceleration by doing that.

I think they will get you going where you want to be...

The canister portion of the pipe makes about 25% of the power and the header is about 75%. If you got like an FMF or something you could always buy the header later on down the road.

A slip-on with the air box lid removed and jetted correctly will be a nice power gain.

You can run an outerwear lid or like on mine, I cut half of it out and then drilled holes in the other half.

I've never had any problems with a stuck lock nut... I don't know

The extra airflow is going to put you lean if you don't rejet. Lean is bad. What ever pipe you choose, that company should be able to tel you what jets will put you in the correct area.