I have a Viper 500.4 for sale. I got this amp as a trade off with a friend. I can guarantee it works because I was the one that took it out. It was prolly used for about 7 months. Cosmetically its not in the best shape, I would rate it a 5 but it works 100%. Its rated at 75x4 at 4 ohms and prollly puts out more. I cna get pics if any1 is interested.