Re: Speaker upgrade/Sound system specs
Sounds like you amp may be hooked into a power source that is effected by the restarting if the engine. I specifically avoided an amp unless it was needed, but you need to have the amplifier connected to a power source that is unaffected by the ESS system. There are quite a few that are. I would get a TH wiring schematic and figure out which ones have no issues and change the wiring over. Usually a wiring harness from the head unit is used to power amplifiers and they can be expensive.
As to using some OEM sub, I would look fir a decent yet inexpensive sub on Crutchfield or other good audio vendor. The OEM stuff sucks. IMHO Kicker name decent sub woofers, but when coming to regular smaller speakers tend to not be my choice at all. Much is about the materials used, the resistance and output keeps as all this naggers. I think Polk and others make great subs too.
Again when secondary amps are out in the large cable wire harnesses usually require pulling up some carpet running towards the back and while it sounds easy, there are a ton of pitfalls to avoid. Hopefully it will all work out just fine. That popping if left unchecked could be a power surge that may end up blowing out a speaker in the future so definitely get that taken care of. Hopefully you have the circuit testing equipment and such testing the different change,s coming from the amp to the speakers making sure equal splitting and that you are remaining under the max guidelines for each speaker. All Amos are not created equal. Be sure you use decent equipment, rather than having to repeat the process again and again. You want to pull the power to the amp direct,y from the head unit over just cutting into the wiring system as it's designed to be done that way. It can theoretically work in other ways but that's when you run into hiccups.
Best of luck. Keep us updated.