Read the manual for the stock Kenwood player.
There's a settings for the balance between left and right. 0 means equally balance.
I recommend to change a new component speakers set come with cross over and tweeters. 

Yours are new car right? IDSI should come with the Kenwood player.

dude, if you don't mind paying a bit more...go to Golden, it's a shop behind Hong Leong near the big Bukit Jambul roundabout... you know the new shop lot place called i-Avenue? the Hong Leong bank over there, behind it only...

you go find Uncle Yeoh...he already fix a lot of City cars so i bet he knows what to do already without spoiling anything...
me also planning to fix my ICE there...but now waiting for the replacement panel for my built in CD player...

Hwy redevil, how much you bought your tweeter? what brand? I might wanna add to my vtec as well ...

Perhaps you can give it a try. Prepared yourself a mini tong of petrol. Then start measure the distance until the car actually started to "dry out", in this term the car engine will just goes dead. Then you can add the petrol into the petrol hole and start the car again. At that time you've already got the actual milage reading.

However, i heard it's not that good for the engine to run until petrol dried out. And it might take a while for the petrol to reach the engine after you refill the petrol manually. It's not a good experiment to perform but it is a good understanding/knowledge for yourself on the car you are driving daily. At least you'll know how far you can still drive if you missed a petrol station on the highway.