It comes down to which dealer you go to. You will find that some dealers actually like selling TRD parts, and those ones will give you full warranty on them (Castle Hill Toyota, NSW, for example; STi Docklands, Melbourne, as another) I'm fairly certain that there will be at least one Mazda dealer who specialises in MazdaSpeed stuff. Also, different dealerships will give you different responses regarding warranty - some of them see it as a factory part (which in essence it is). In general, I have found most dealerships to honour your warranty unless your modifcation caused a failure, in which case the failed item will not be covered. For example, if you are having warranty issues with your suspension, however you have done engine modifications, then it will not affect your suspension.