When you are looking at power, RMS is the only thing that matters. Peak power doesn't tell much at all. I highly doubt it will be 160watt RMS, especially on some generic brand. Did everything work correctly before? Or are the speakers the newest addition? Did you buy them new? Do these speakers have an external crossover? If they do and you wired them correctly or if you don't even have them wired in at all it will cause you problems. Does the head unit power the factory speakers just fine?
"We live for a good time, not a long time."
RIP Colin McRae