Hyosung GD250R FI LIGHT

Hello mates, i’ve installed a new exhaust on my GD250R and now, after minutes of riding I get the FI light on, following the manual it is an injection problem. Why the new exhaust caused this? How can I fix it? ( I also have a BMC Air filter ). Also, I spoke to a racing mechanic who works with this type of engine but he said he doesn’t want to mess with this motorcycle and to talk to the Hyosung Dealer in Portugal to connect the motorcycle to the machine and adjust the injection values. I called the dealer and they say they can’t do that. Tried another mechanic and we think that the BMC Air filter is messing this. Waiting for the original air filter to test.