Im not to familiar with speaker systems but i wanted to add a little more bass to my stock car stereo system for cheap.
for cheap? get a cheap secondhand subwoofer/ cheap box/ wire it to the stereo… Im trying to remember a mod people were doing on the first ten that boosted bass a little but not sure if it works on second gen… the above can coast as little as $100 or less you just need to search local listings etc.