What are you going to be powering with it? RMS is 50 x 2 @ 12.5v and bridged RMS is 280w x 1 @ 14.4v. Its a decent amp depending on what you are going to be running off of it.
Unless your looking to turn the MTX into a 2 channel amp at a later date, you might want to look in the mono JBL's. They'll give you all the power you need at the best price.
what about in comparison with my old kenwood 600w (600w is just the model , I think it only produced about 300w) because It really pounded the sub. would this one do the same?
Dollar for dollar and watt for watt the Kenwood doesn't hold a candle to the JBL's. If you already owned the MTX4202, like I do, I would say use it. But since your actually purchasing it, the JBL is a much better amp for the price.
I agree, dont buy the MTX 4204 unless you are planning on adding in a 2 channel later on. You would be happy with the JBL. I do like both, the MTX looks good, but I think the JBL would out-perform it(maybe?)