Dear wise NAM users,
I am getting ready to install a small subwoofer in the back of my R53 and I had a few quick questions. I have taken a few screenshots from here to illustrate some of the questions.

Rear-speaker wire access: I have found plenty of resources online (mainly this forum and mini2.com) which go over the process of accessing the rear speakers which allows for changing the speakers and tapping the rear speaker wires for a line-out converter. However all of the write-ups assume that one is changing the rear speakers as well. Since I am planning on keeping the stock speakers in the back (they are working fine, I just want some lower frequencies), is it possible to access the wires for the rear speakers without removing the seats and wall panels?

If accessing the rear speakers is the only way to get to the rear speaker wires (aside from going through the head unit), is there a place that I can tap into and carry the wires so that my lines for the subwoofer are not pinched underneath the speaker boarder/edge? This would be related to picture 1, is the green encircled wire harness the speaker wires?

With regards to doing the full disassembly to access the rear speakers, does anyone know the part numbers (or an equivalent working parts) for the rivets/clips in pictures 2 and 3? It seems as though there are multiple of the rivet clips from picture 2 in the trunk and side moldings and there are four of the yellow pop rivets from picture 3 in the trunk molding. I just want to have some on hand for when I possibly/likely break the originals during the installation.

Thank you in advance for your time.
Picture 1: Exposed wall panel with a wire harness arm/extension
Picture 2: Rivet clip found in the trunk and side wall moldings
Picture 3: Yellow pop rivets found on the trunk molding

Going to move you the Nav/Audio section. ECS is a vender here and has a good knowledge on all the different screws/clips/hardware.

I have no idea what you meant by a small subwoofer. Smallish subwoofer is counter productive. Mini already has 16x9 speakers at the rear. The problem is with all factory speakers they are crap, standard issued or sell-up fancy hi fi haus branding that lacks substance. You will improve the sound across the audible spectrum if you just replace all the speakers judiciously with aftermarket ones. 16x9 speaker is likely to have more surface area than the small subwoofer without the need to find a place to house it.

Thanks for the reply pnwR53S. When I said small subwoofer, I meant in comparison to custom builds with powerful amps. I friend of mine recently upgraded his audio system and offered me a practically new Rockford Fosgate P300-10 for $50. This is a 10" boxed unit (not a compact under-chair subwoofer) with a 300 W RMS amp and a frequency range of 35-200Hz. It fits nearly perfectly laying flat, on its angled back, in the boot without any modifications. If I am not mistaken, the back of the MINI has two 6"x9" speakers which have a little more than half of the surface area of a 10" circular driver.

If I have to open up the side panels to access the rear speak wiring then I may choose to replace the rear speakers, but I don't like replacing what isn't broken. I have been fairly content with the sound of the rest of the standard system (I don't really blast my music, I like the sound of the super charger too much), I just want to add support for the lower frequency range.

You do have to remove the whole rear plastic panel to access the speaker wiring. I can tell you from my own experience with a set of cost effective 16x9s there is no shortage of bass, unless you want your neighbours to hear thum, thum a block away. When I did mine I added small amount of acoustic mat to the sheet metal. Those factory paper cone speakers are worthless so the biggest bang for the buck is to change them all out. Efficiency is key and you can achieve very good sound with just the amps in the modern aftermarket HU that are all bridged amps.

Don't forget there are two 16x9s vs one 10" subwoofer when you compare the area.

16x9?? You mean 6x9.

You can't compare subwoofer to non subs by size. Doesn't compute.

Cheers pnwR53S, I guess it wouldn't be a MINI if the installation, or access of wires, was more straightforward. When you did your installation, were you able to see if the wires circled in Picture 1 (beginning of the thread) were the speaker wires? Even if I choose to replace the 6x9s, I don't want to have the wires to the subwoofer being pinched behind the speaker baffle. Good call on the acoustic matting, I think I have some of the lying around from another project.

I completely agree that if I change all of the speakers and upgrade the head unit, or add an amp, that I would then have a fantastic sound system in the car. However, I can't think of a better way to increase the low end frequency response of the system while keeping the stock head unit and front speakers other than adding an amped subwoofer (and one I was fortunate to get for $50). Especially since there seems to be a fair amount of different opinions as to whether just replacing the speakers (without changing the head unit) does much considering the stock HU is only putting out <5W of power, unless of course if any of the speakers are blown.

The combined surface area of multiple speakers doesn't mean anything as to the frequency response of the system. Two 6"x9"s, or a thousand 2" speakers for that matter, will not compare to the <100Hz response of a dedicated subwoofer. Depends on the genres of music you listen to, but I want to feel my music well before reaching ear bleeding volumes.

Thanks Minnie.the.Moocher, you beat me to it

I know all too well most discussion of audio fidelity can be very subjective. I agree with you when it comes to low frequency reproduction one cannot compare the surface area. However in a small cabin a good pair of 6x9 full range speakers can sound very good if you are truly after high fidelity, as opposed to over the top boosted low frequency bass.

I swapped out the factory HU right from the start, and the speakers soon after. There is nothing to be sentimental about keeping the stock HU especially you want more overall sound pressure. The worst you can do is the have too much bass and excessively offset the frequency flatness, which I see all too often with people installing subwoofer and ignoring the much more important sub-spectrum where voice and most voice-like instruments reside. A flat frequency response even with constrained high and low is much better than exaggerated high or low ends.

I did not take note of the speaker wiring access but common sense tells me MINI designer take the least distance to route the wiring. They must run along the sill (likely on passenger side) which is a PITA to intercept there, and to the rear speakers.

My advice is if you want to improve the sound fidelity:

• Buy an aftermarket HU with BT - any name brand as most are built in the same factories with very similar design.
• Replace all the speakers - you don't need to spend that much these days as most are very good.
• Add acoustic damper mat to the rear - the front are fine without as they don't go that low nor much low frequency energy.

Cheers. I am by no means an audiophile and I know that a 300W subwoofer is on the excessive side for pairing with the stock system. I don't expect the subwoofer to be running at anywhere close to its capabilities. All of this was motivated by playing a favorite track of mine, having my MINI disappoint me for the first time with its playing of the track (complete lack of the necessary low end) and then conveniently finding out that a friend was planning on selling his sub. While it is by no means a Hi-Fi system, I really like the consistent aesthetics of the center dash with the stock HU, but I think I will replace the rear 6x9s if I am already having to access them for the wiring. That said, once I blow any of the front speakers or damage the HU from having too much fun with the subwoofer, I will look into replacing the front speakers and the HU
Did you install the acoustic matting inside the wall cavity or between the sheet metal and the plastic molding?

300W

I only put a layer on the outer body sheet metal. Never any sympathetic resonance even playing very loud. Anything more would do nothing but adds weight. The front door panels already have factory sound deadening.

Cheers pnwR53S, I will install with the acoustic foam on the outer body sheet metal and I found some relatively inexpensive 6x9s to replace the originals while I am already behind the body trim.

I think I found the parts that I referenced in pictures 2 and 3. For anyone else looking to replace the plastic bits (on a pre-facelift R53), from realoem.com wall panel and boot panel pages:
- The black expanding rivets in picture 2 are part # 51118174185. There are three of these on boot trim panel.
- The yellow clips in picture 3 are part # 07131503417. There are four of these on the boot trim panel and six on each wall panel.
- There are three spring clips (part # 07149198818) in each wall panel that were pointed out in the video.
- There are three expanding nuts (part # 07130672440) paired with three self-tapping screws (part # 07146977198) in each wall panel. These look like they will survive reuse if not cross threaded.