Bikes come from the factory running as lean as is acceptable, for emissions and fuel economy reasons. Adding a higher flowing air filter and/or exhaust will push your fuel ratio even more lean, which is not something you want.
A slip-on exhaust won't change much, but if you're getting a full system it can upset the air fuel ratio. In that case, you'll want to tune the bike with a fuel controller or an ECU flash. Same goes for the air filter if it flows more air than stock and your bike isn't able to compensate for it.
If you're just getting a slip-on and the air filter flows the same as stock, it will be fine.
"It’s true that modern bikes run on the lean side of the air/fuel mixture spectrum to help meet emissions." - http://www.motorcyclistonline.com/does-your-new-motorcycle-run-too-lean
"When you upgrade your bike with a new exhaust system, air box or hi-flow air filter it may upset the air to fuel ratio creating a mixture that is too rich or too lean." - http://www.weeksmotorcycle.com/Carb-jetting.html
"Which is why we have products that allow you to retune the fuel and ignition systems to improve performance and accommodate changes such as a different exhaust or air filter." - http://www.motorcyclistonline.com/all-about-tuning-your-bikes-efi-adding-power-commander-or-reflashing-ecu-motorcyclist-mc-garage-tech