Do I need to upgrade my electrical with this equipment? (SA-12 build)

[USAFMileHigh]

First official post on the SMD forum, have been using it for alot of information recently (no need for a "welcome" post, I've seen a generally high quality of character on here(: ). Worked car audio for BestBuy for 3 years so I would consider my level of experience intermediate.

CURRENTLY this is what I have:

2006 Cobalt SS Sedan

BRZ-1700.1D Amplifier

4 awg Rockford wiring

1 SA-12 D4 (running amp at 2ohms to sub)

2cuft custom ported box tuned to 34hz (built myself)

1 Rockford farad capacitor (yeah don't judge, put it in years ago on my old Infinity Kappa system)

600CCA 330 Load test Amps ACDelco battery

130amp Alternator Stock (I believe, have to double check)

GOALS:

Adding another SA-12D4 and running the amp at 1ohm ("1700w" rms split between the two)

Building a ~4cuft with probably the same tuning

Most likely sealing off the trunk if I can figure out how to do it without ruining my trunk

Now, my question is do I need to do the Big 3 on my vehicle and/or add/replace the battery before adding another subwoofer? Replacing the Alternator is well out of my budget, and I with the battery being located in the trunk, I really don't feel like tearing apart my car to do my Big 3. I'd rather just pick up a 2nd SA-12 so each sub is getting a -maximum- of 850w RMS instead of the max 1200 RMS the single sub is recieving now. I know I SHOULD upgrade the electrical to get the most out of the subs, but do I NEED to with what I am running now? Will it harm anything?

To recap, I cannot get a second subwoofer AND upgrade the battery/add a second. I also cannot afford a new alternator, and the Big 3 really pushes my budget considering supplies for it alone are $100 for the 0 AWG + terminals(ring and batt), including the parts to crimp and solder I don't own and the knowledge to correctly tear apart my car... don't wanna pay BestBuy $80 to do it either.

Thanks for the input in advance Oh on a last note, keep or ditch the cap and why?

[michigancapri92]

Always big three no matter the equipment !! And to say you can either get the subwoofer or the electrical ... if you get the sub and don't upgrade your electrical and you blow something ... was it worth it .... when building a system always upgrade your electrical and build the system around your electrical ... not the other way around

[c.director]

I would really look into upgrading electrical.. I think you gonna be pushing the limits of a stock system, you will probably see 11 volts occasionally. often.

[USAFMileHigh]

Any guess what voltage I am looking at by upgrading the Big 3 to 0AWG? Brandwise I was thinking KnuKonceptz or Cadence due to price and reviews since I'll probably get a 25ft spool (battery being in the trunk). I can get Big 3 and Sub its not really a money issue, its a tearing the car apart issue and tools issue . Would that be enough for stable electrical?