hi there.. i have some query
my budget is as low as possible..RM100-200
i want to improve the bass effect of my front door speaker.
now my car front door have no soundproof at all, except the cotton-like sheet at my door trim
what should i go for?
1. a sheet of stp gold/silver apply at the door metal and that's it
2. pair of stp crystal apply at the back of the speaker and that's it

i dont bother the rear door. PLease advice and thank you so much for your attention