What gas to burn?
 

what is s4 TII tuned for from the factory? I been buring premium and the previous owner has too but I know for my bike it is tuned for 87 octane and you wont see any power gains but only get more carbon build up in the engine. Sorry if this has been discussed before.

In stock trim there is no need to run anything more than 87 octane, and using anything higher will actually result in lower power on a S4 rotary engine.

ok that's what i wanted to verify. thanks Icemark.

I've got a s5 TII with some basic mods.... upgraded secondaries (720cc) No emmissions, 3" downpipe, FMIC, etc, and was told that I should only run 93 octane in the thing or it would kill the motor. Anyone care to elaborate? I'd love to save some money at the pump! (....... so why did I buy a rotary?)

In stock form, you should run 87 octane. Once you start modifying it you should use premium since it has better knock resistance.

If the car is modded (and turbo), run premium.

Yeah, NA's should always run the lowest octane you can find.