I have the audiophile system in my 05 FX4 and I love it but would like to upgrade the sub. is the amp external on these systems? if so, does the audiophile headunit produce a strong enough signal to produce a good frequency range and sound quality on an aftermarket amp? I'm thinking of getting the JLW3-4 8" sub, will this fit in the original enclosure, or should I just scrap that enclosure and build my own for a 10 or 12? also does an aftermarket HU make the system sound any better? thanks

 

Yes a HU make it sound 1000x better. And dont do an 8" sub, do at least a 10" with a new amp.