Downshift in Automatic?

I have an automatic as many, but not all, have in here. But i like downshifting from 4th to 3rd gear to gain some extra speed on the highway or when i'm just messing around with other cars. Is this bad for the engine?? I would think it might mess up the Tranny's or just add some 'wear n tear' on the engine. Does anyone have any information on what consequences could arise from this because i've asked many people and they have mixed opnions. So thought i was bring it up on here. thanks.

the higher you rev your engine, the more wear there is on the engine. as for the tranny, if you make your car downshift by pushing the gas or you downshift manually, well its the same.

yeah its not really recommended practice to downshift the slushbox, but if you do it occasionaly in the race or something, the tranny should still be fine.

You should be fine. The automatic tranny does know when to downshift on its own though