Did you change out the speakers or just amp the factory speakers? After lookin at my shaker 500 speakers I couldn't imagine any more sound being mustered out of them. To get a real performance boost from an amp youd have to change out the speakers to something that can take the added power.
All speakers, and the head unit have been replaced. I actually enjoyed the factory Shaker 500 system more, but this system came with the car. It also came with a horrible wiring job that took me 2 days to fix, but that's half the fun in owning a mustang, tinkering with it!
I can get plenty of power out of this system, but it just never seems to "balance" out the way I like it. I can set it up great if I'm in a heavy metal mood, but if i'm stuck with one of my friends (that has a really nice rack) that likes techno, country, or something else then the settings go to crap. I might also note that i'm extremely fussy and picky.
If it wasn't so expensive, I'd pick up a factory shaker 500/1000 Head unit, and upgrade the rest to shelby's stereo system.
07 Mustang GT Metallic Alloy.
FRPP CAI. SLP Loudmouths.
Roush Front Bumper w/ chin spoiler, Roush Hood scoop, Scott Drake Hood pins, Roush 1/4 window louvers, Billet fuel door.