Just installed the Aura RPM 4" speakers. I used a closed foam gasket to line the speaker bracket before installing the speakers. This helped seal the speakers as well as form a baffle. The finished product was remarkable. These speakers have good low end and very neutral highs. A subwoofer blends beautifully with these in the front doors. The transition between woofer and tweeter is very smooth and sound is very full and well rounded. The build quality is superior to the big name brands that are out there. I've had so many sets of speakers in my car. I've been chasing a particular sound for years and always fell short with the big names. For $23.00 I found music bliss. Very happy with these and appreciate the members on this forum for steering me to purchase these. FYI, these are powered by an alpine head unit and complimented by a bazooka bta6100. End result is sound quality, not spl.