You really want a system that gives a dry spark (fuel cut), cause if the engine is running at high rpm and high temp you can ignite the fuel in the cylinder. You will never ignite just air in a cylinder.
By cutting the ignition you end up pumping fuel in to the exhust and then you shoot flames every where.
Looks good, but the turbos dont like the excess heat that this produces. You can also blow the baffles out of you exhaust.
Most stand alone ECU give you the option of fuel cut or ignition cut, This is due to different people have different veiws.
Please take in to account that this is my own point of veiw and i know that some of you will not agree.