Fake speakers will never ever sound as good as original, to begin with. If it ever sounds better, the original company should just close their business. Secondly, even in the wildest dream that the fake brands sound better, it won't last long due to the quality of materials used.
Generally, if you're looking for reputable brands, try to go for bigger and famous shops for installation. Their more likely to sell genuine products and besides, you won't go wrong with their installation job. Also, if you happen to see a Soundstream amplifier selling at half the normal price, you might wanna think twice. I've seen a MTX amps that looked so much alike the original one. If you put side by side, you really need to closely inspect the finer details, only then you know one is fake. But the fake one is selling almost 1/3 the price.