This mod is one of the most satisfying jobs I've done on my Z3, true you could have one with HK already fitted but even that can be made better as
@Antm72 has described in detail elsewhere on this forum. I was spurred on by Susan's efforts /plans and finished product, thought it might be beyond me but look at the pics and decide for your self.
Now mine is wired and working giving me the extra bass fill in from behind I'd like to thank Susan for the great write up which spurred me to go ahead and build it, shame its taken me 18mths to actually wire it up. Here's what I achieved and hope others will now follow suit to get the sound which the Z3s without Harman Kardem system deserve and should've had.
If you look carefully you'll notice the port under the lower speaker grill, decided to go this route because no one else had. Wether it actually helps the mid woofer perform is debatable but I like the sound and being no expert this being the very first ICE I've built. Did use two amps, one Alpine KTP-445A intergrated with the Alpine head unit and Hertz speaker upgrade designed for the Z3. Plug and play amp with only the location to worry about. Thus under passenger footwell was easy install for me.
The second amp was a Bass Face DB4. 2amp to run the Pile Gear X 6.5inch mid woofer. (amp sitting on passenger seat ready to go up under passenger dash where the later air bags are fitted)
This amp needs a seperate feed from the batt but I wasn't prepared to go from the boot so here's what I did and works very well as the amp will not draw feed untill the head unit is switched on and that's governed by the ignition so wasn't unduly worried.
As seen there's a short run to the in line 2amp fuse then (nice new red 8amp wire) on along the bulkhead firewall to the washer bottle down behind it to spare unused grommet lower firewall, pierced it to take feed wire into passenger footwell then up to Bass Face amp under dash, much easier and quicker than from the boot. IMO.
The speaker wire from the new mid woofer was partially installed before mounting the woofer box into position hence availability to conceal its route to the passenger side where it travels under carpet to footwell keeping it away from interference from main wireing that runs along the centre tunnel.
There's loads of info for fitting ICE into Z3 on internet but mostly systems fitted with larger amps in boot. I went with Susan's woofer box plans useing smaller amps with less power but reackon I've got real nice sound with no loss of extremely valuable boot space. The system in my Z is good enough to keep me happy at medium motorway speed and good enough for top down driving in mid range revs, not that it's used much in good weather top down driving, the engine exhaust note keeps me happy enough. Building the box was easy enough for me but adding the port was very trial and error, so why have I covered it with a second speaker grill, because I just had one spare and like the look better.Heres what it looks like with first borrowed speaker, you can see the port.
RHA,Roy