EFI doesn't tend to run lean when changes like this are made like carb atv's do.
EFI measures airflow and gives fuel to match, Making simple changes like this will not adversely effect it. On carb atv's pressure changes from free flowing exhaust and intakes will cause a lower suction across the jet and make lean conditions. Works the other way also, If your intake is really dirty it makes a higher suction across the jet giving you a rich condition.
I couldn't disagree more......IMO swapping to an aftermarket slip-on without a fuel controller is just asking for problems. KA-BooooM !
The 700XX uses a rather simple form of Fuel Injection known as "Open Loop". This means that the fuel injected in to the engine is a set amount and is only altered when there is a measured change in atmostpheric conditions.......eg: high altitude. It does not automaticlly adjust when changes are made to the engine like exhaust systems and free flowing filters.
If you change intake or exhaust conditions (more free flowing) then you will lean out the air/fuel mixture.......if its easier to get air in to the engine then it will need more fuel to match. The computer will not adjust this automaticly.
Seeing that the stock 700XX silencer is very restricted, an aftermarket slip-on will make a large difference to the "flow" of the entire engine and you will need an aftermarket fuel controller to bring the engine back to a safe air/fuel mixture......a byproduct of this safe condition is more power.
Linc
