Would this be a good idea to get more bass or stupid? I have the stock Pioneer subwoofer...

 

Modifying the stock box with the stock sub in it isnt a good idea. but im not really sure what you mean by adding a port near windshield

 

I am just talking about cutting a hole behind the rear seats. Would that increase the boom in the interior?

 

No

 

Get a bigger sub. I had a 12 inch in my last cobalt and it did the trick. It was nothing crazy but being a small car you can feel the bass. I think the amp was 450 watts rms. I think the sub was a fusion sub. Cheap at best buy but it worked lol.

 

Lay the seats down, and build a nice system (no prefab box)

 

ya probably not so much

 

Okay thanks for the advice. Will not cut.