you know what is the best front speaker that fit our Z. I dont want to do any modification so I am looking for plug and play kinda type.. http://www.crutchfield.com/ has one but its so damn expensive.

 

quaility speakers will require a spacer plain and simple. The window is only about 1" back from the speaker hole. To get away from using a spacer you would need a speaker with a very small magnet or oddly shaped magnet. Do yourself a favor and use the stock speaker as a spacer or cut out a ring from a piece of MDF wood.

 

Take a look at this link: http://liljerk.morpheus.net/350Z/front_speakers/

You will see how close the window really is to the mount location. Spacer is the only smart way to go.