yeah hes talking nonsence, there is no way for the engine to know wether there is an air filter or not.
youd get away with none for a while before you even caused much damage unless it had a MAF sensor. my mate used tights on one of his minis, went up nicely when it forefired:ROFLMAO:
hes pulling a fast one and hoping by saying this he'll get away with it. DONT trust him.