Kushagra,
Please dont 'quote' if you are replying to the last post.
Sound Quality - After market HU would be better than the OEM one. (It doesnt mean that the OEM one is bad). This would have to be driven by budget.
One of the reason why aftermarket HU would be better is because, it offers you better controls. Sad thing would be that you wont be able to use the steering controls.
Small vent - here is a sample.

Source: TBHP
This will allow your 'BASS' travel easier to the cabin.
Damping - Here is a sample:


This would reduce rattling/Vibration and the audio would sound better.
Note: Damping sheets would be vary in looks, size and cost.
Dash panel: Here is a sample.

Notice the portion where the HU is placed. The Darker area is the replacement of the OEM HU. So you would need a dash panel like this, into which your HU would go.
In this example the person has chosen a single DIN stereo.
Another sample done in Civic:


Note the difference inside the circled areas. Here the colour has been kept intact unlike the first one.
I am not sure about the life of the door & speakers.
Opening the dash panel doesn't void warranty. However tampering with the electricals will.
|