I agree.... I'd think it would help, but apparently Biff doesn't agree. I already added a sub (10" Infinity). It definitely helps with the low end, but the mids and highs still need work. Some recordings sound really good (especially accoustic), but for an upgraded JBL system, I guess I'm pretty disappointed. I'm really looking for a way to make things better without replacing the HU and having all the headaches that come with it. (steering wheel controls, rear seat audio.... not to mention ripping the whole dash apart) I would also really like MP3 capability. I've started to look a little bit at the MP3 CD changers that use an in-line FM Modulator connected to the antenna wires. WXMAN13, I'm really interested in how your speaker replacement goes. Since you have the nav system, does that automatically mean that you have the 10 spkr JBL as well? I also inquired about speakers at Crutchfield. They said that they have done "research" on our vehicles, but they do not have a mastersheet yet. They said that they have doc's that the tech support people can use to walk you through things, but they didn't yet have the nice sheet with pictures and the step by step process to install your new equipment.