GNBRETT

I have a 2013 Turbo Mustang GT SINC and looking to build a system. this is what I currently have:

1.) Memphis 5 channel amp 1400 watts. (1 year old)
2.) JL Stealth box (I know this wud not be my first choice but weight and trunk
space are important to me since I race the car)
3.) Rockford Fosgate 4 channel amp not sure what model a couple years old.

what I need is a Head unit and front and rear speakers and maybe a DSP. Does the 5v preout sound better then a 2V if you add a DSP to the Head unit?

The only Head unit with 5v pre outs I can find is the Kenwood but I keep hearing the there is a "Hissing" noise coming from the Apple Carplay with this unit. seems to be a common complaint.

if I opt for the Kenwood which has a built in EQ will I no longer need the DSP or will the DSP improve my sound either way?

I don't care about the SINC. in fact I'm gonna disable it. I was looking at the Alpine ILX-107 cause it has wireless Apple carplay ability so no more plugging in phone kinda like the SINC sorta but it only has 2v pre-outs. Can a good DSP clean that signal up or do I need to have 4 or 5v from the head unit?

Was looking at Hertz MPX 690.3 for the rears and Hertz MLK 165.3 up front.

originally I was looking at putting the Mille MLK 1650.3 with the bigger 1605.3 woofer at 7 inches and bi-amp em but I don't think I'm gonna be able to afford that. its like another $1400. to be honest the sound from the MPX 690.3 was so freakn good I just assume the MLK 165.3 wud be insane.

how much BETTER is the 1605.3 set up gonna be over the cheaper one?

any advice would be appreciated?