Problem With Mach 460: Aftermarket Headunit : Bass Cut Off On High Vol
 

Hi Guys,
I am sure this has been asked multiple times before, I tried searching but could not get the ans.
I have mustang 2002 V6 convertible. With Mach 460 (I guess so because I don't see any sub in truck and only 2 amps back to the rear seat).
Mach 460 comes with 2 amps, powers front door and rear speakers and my 2.5 tweeters are getting power directly from HU.
I have installed pioneer headunit with front door speakers with Infinity (6x8). Rest all stock.
Problem : When I increase the volume more than half, bass cut off and then comeback in few seconds.
As fas as I understand, this is happening because my stock amps are powering to all door speakers. Stock speakers are different ohms than after market (4 Ω), so when I increase the volume, amps goes in protection mode.
I need suggestion :
I am planning to replace my rear speaker also with 4 Ω too and plug off all the tweeters and connect the tweeter wires to Speakers (Door and rear). As tweeters are directly getting power from head unit (i.e. 4Ω output) they should work with door and rear speakers.
And later add a 10" sub with after market amp with stock amp output.

o ya .. I am using Metra 70-5519 Wiring Harnesses to connect aftermarket HU.

Do you guys think this setup is feasible and will deliver good sound?
Please advise.

Thanks for your time.

Some more information.

This is the head unit, I am using.
http://www.pioneerelectronics.com/St...Manual0917.pdf

This is how I have wired it:
https://mustangboards.com/show-shine...-mustangs.html

Any one please advise.

So here is the update,

The setup I described in my very first question here, works AWESOME.

Thanks