Now you have to understand that not all cars come equipped with a state-of-the-art sound system. There are a number of cheaper audio system options that companies put in and they might not be fulfilling your audio needs. Now there are several cheaper ways you can not only improve the quality of the sound of the system but also make your speakers louder. The first thing you would want to do, to make your speakers loud is to dampen the car noise. Oftentimes, it's the ambient noise inside the car that might weaken the sound of your audio system. What you need to do is add insulators to dampen the sound coming from your engine. You can also purchase a subwoofer, as they are relatively cheaper than an amp. Alongside that, an external speaker or better wire connections might do the trick for you.