The injectors are a little noisy and they're installed over the top of the engine, so I would say that you would need to consult your gas installer in order to be able to replace spark plugs and coils. Other than that, with a simple tune (again, consult your gas installer), you should get some good fuel economy figures and perhaps a little extra torque in the low to mid range. My advice is to find an installer who has a lot of experience with AEB gas injection ECUs, specifically the BRC Sequent systems.
Injected CNG, LNG & LPG: The only way to go better!