Started looking at head units. The Pioneer DMH-2000NEX had the feature set I wanted at a very affordable price. Picked that up off eBay refurbished for $250 shipped. Also nabbed an install kit and harness. I still wanted the steering wheel controls to work so the PAC SWI-CP2 was purchased from Amazon.

The installation went fairly well. Had to modify the mounting brackets to get the radio at the right angle to match the opening. I'd have to say it came out really clean, pretty much looking factory.

I chose the radio because it allows the front and rear powered outputs to be configured as tweeter and midbass. It also has time alignment.

https://www.parts-express.com/4-x-6-High-Excursion-Poly-Cone-Woofer-with-Neodymium-Magnet-299-714?quantity=1

1 cf is the max we can fit.

What are your thoughts? Is this a lost cause? Should I just buy a GRS subwoofer?

On the left is a pair of Beyma 8P300FE's. Nice and beefy.

On the right is pair of B&C 8FW51's.

Here you can see the 2nd Gen CSS SDX10 on the Left, and 1st Gen on the Right.

MAX kit:
https://www.jlaudio.com/pages/max™-audio-measurement-system-overview

Live stream link:

The sub is a 7 or 8" paper driver with dual 2 ohm coils. Plastic frame, paper cone, QTS=.95, SPL=86 db, VAS=11.4 L, FS=51hz, SD=200cm2.
The output of the sub is very low.

I looked for a high efficiency dual 2 ohm Sub and found nothing. Then I wondered if I installed 4 x 4ohm woofers in the empty spare tire area if that would be better. (I really don't want to add an amp right now.) This would get the spl up. But would it sound like crap?

Anyone ever tried this before?

Tweeter - https://www.madisoundspeakerstore.com/soft-dome-tweeters-sb-acoustics/sb-acoustics-sb21rdcn-c000-4-ring-dome-tweeter-neodymium/

Mid - https://www.madisoundspeakerstore.com/approx-4-fullrange/scanspeak-discovery-10f/8414g-10-4-full-range/

Woofer - https://www.madisoundspeakerstore.com/approx-8-woofers/morel-caw938-9-woofer/

Thanks for any thoughts and recommendations.

The issue with these subs is the port. I am looking at a 20 or 25L box tuned to 30 hz or lower. Seems like a good candidate for a PR. However the PRs on the market are almost as much as the max-x driver! Any suggestions for a high value PR? (The css10" at $90 looks like the best deal)

Or should I do 2 opposed subs sealed for almost the same price?

I have posted this issue on several car audio forums where the overwhelming response is that I need load resistors. However my understanding is that load resistors are for when you remove the speakers to load the amp.

I am adding the amp's high-level inputs in parallel with the speakers. This is adding a 5k ohm load in parallel with the speakers. I don't see how load resistors can be added.

I think that the amp is causing some sort of distortion that the hu is detecting.

https://www.erinsaudiocorner.com/driveunits/dyn_mw172/

This isn’t truly a shocking revelation.  Plenty of people already do what I suggest.  It just goes against intuition and against some beliefs in the car audio community that a subwoofer should not play too high in frequency because it can cause the bass to be localized behind you.

The reason why is due to one MAJOR issue in car audio: the “Nearside Null”. This is the large dip in response of the driver’s side midbass speaker that occurs typically in the 70-90hz region.  This doesn't occur in every car; there are certainly exceptions to the more extreme car installs.

It is an acoustical null caused by the relationship of the listener’s location relative to the midbass location and generally caused by the width of the vehicle. If you play a track with bass guitar it’s very prevalent; you get a localization to the nearside midbass speaker when the midbass speaker is crossed lower than the frequency where the null occurs.

Generally speaking, the lower your crossover point between midbass and subwoofer, the more noticeable this occurrence is. Unfortunately, this isn’t something you can simply “EQ out”, either. Throwing +6dB at this null may only result in 1dB of actual gain; that means you’re wasting a LOT of power and risking damage to your speaker for no acoustical gain. Some of you may even think to yourselves “seems like you’re not getting much by crossing the midbass low. Maybe there’s not as much benefit as I thought in doing that”. That’s a logical assumption and a lot of times that’s actually true. Crossing the midbass too low can actually result in more “bass behind you”! And you can also take some of the strain off your midbass by crossing them at or above the null. Ironically, we in car audio tend to cross midbass low to get the “up front” bass we so much desire. BUT, IN FACT, the majority of the time you have bass that pulls to the rear is BECAUSE of the midbass nulls. I know that sounds counteractive. But it’s the truth. Standing waves are problematic and this is one symptom of them; whether in home or car audio.

Contrary to popular belief, raising the subwoofer crossover in to the region that this null occurs can actually HELP the sound to stay focused and achieve “up front” bass. If you can move your subwoofer to a location where it is null-free through a frequency above the Nearside Null then you can likely improve midbass without negatively impacting the “up front bass” effect that so many are after. And you can also take some of the strain off your midbass by crossing them at or above the null frequency. Not all have the luxury of space to move the subwoofer around much but experimentation is key here; you may be surprised at the difference subwoofer placement in the trunk can make.

And one important conclusion here is that placing the rear mounted subwoofer on the opposite side of the listening position often results in better response!

Anywho, my wife and I recently picked up a 1968 Camaro. It was "done" by the guy before me. Overall its an okay car. It is nothing crazy; It was badged as a Z28 by the last owner but is originally a six banger sport coupe. It has a budget 383 choked off by some smog-era iron heads. The body is relatively solid, I'm sure with plenty of glass under the paint. The paint is pretty clean, with some bubbles. It is supposed to be sunset orange metallic, looks coppertone in some lights. It looks, runs, and drives pretty decent. My personal long term goals are to lose the 15" Cragars, drop it a couple inches, put some decent heads on it, upgrade the suspension, and go for a pro touring look.

The car came with a circa 2000 Pioneer CD deck and sweet pair of Kenwood dual cone 6x9s. I like those older Pioneer decks, but this one was all messed up, with the preouts cut off and antenna wire pinched almost all the way through. I pulled the deck and found a nice gouged hole behind all the mystery glue holding the radio in. Being that this was the situation, I had thousands of dollars in old car audio gear in the garage attic, and I want to go pro touring look anyway, I figured I'd do a custom install. I plan to try to blend it in with the car's interior the best I can without hacking the car. I'll try to keep up with progress pics.