If the amp is honestly rated at 1100 watts rms you would need to know what impedance that is into. Let's say it is into 2 ohms. You would want a speaker or speakers that could be connected to present 2 ohms to the amp and that can handle a total of 1100 watts rms. If the speaker was 4 ohms then you would want it to hand;e 550 watts.
Power ratings on car speakers are usually as unreliable as the power spec on car amps so be aware of that, Pay no attention to peak power ratings as they are totally useless.