It does not deal with change of airflow well. You will have to have a bung welded onto you new exhaust for the O2 sensor if the exhaust system is not designed for the FI version Ninja 250. If you are bypassing the O2 sensor you may need a O2 sensor eliminator. There is a little bit of remapping that can be done, but you need the right ECU. If going to a full system you may want to look at what the LeoVince ECU for FI Ninjas has to offer. These units are installed on the 250 Ninjas for The WSBK European Junior Cup. Dynojet also makes a Power Commander as well.....My question is how does the EFI system deal with the change of airflow or do we need to remap it some how ?