Once upon a time, there was a truck. And like every truck needs ICE, so did this one get some. An Alpine 9826 HU, a pair of nice Alpine SPS-170's 6" co-axials at the back and a pair of 4" Hertz Dieci DCX-100's on the dash. All set in stock locations, and playing their tune, oblivious to the world outside. To the beautiful ICE'y world that was there to be discovered.
TBHP was discovered, and life went on. No drag-strip style dash to change anything. The miles went by and the truck found itself in Silent Valley, in the company of a couple of other trucks, and a few others. Like an Elantra, for example. The 'content' trucker even showed-off his (cold) ICE set-up to a mad mullah who indulgingly 'approved' the set-up.

But that mad mullah also did enough to start a slow change. Something that was not very notice able then, though.
Things actually started to change more than a year later (the delay being due to other reasons). The change did happen, and how !
Stock location of rear-speakers :
The speakers in their stock location are at a double dis-advantage. Apart from being partly hidden behind the jump seats, these speakers are also 'hidden' from the front half of the cabin. The middle seat acts like a barrier for the output of the rear speakers.
Alternate locations were explored. While Satya has been helping me with the actual work, I had been talking with an Old Fox by the name Aniruddha. Options that Aniruddha gave included having a roof-mount at the back end of the roof, a-la the yellow board Tempo Travellers. Another option was to use a 3 way setup of components on the dash, the current 6" co-axials at the back, and the DCX-100's doing their bit too. I was not sure how this can be set-up, so kept this option for later exploration.
What I wanted something in-conspicuous, with minimal modification work. I also did not wnat to have additional speaker boxes on the floor, as this would take up cargo / passenger space.
And it helped to have a carpenter doing some work at home. Mulled things over, and things began to fall into place & shape with the help of the carpenter.
The solution : Custom made speaker boxes, aligned to the inside of the D-pillars. And mounted to points readily available in the frame of the truck body.
The location :
A close-up of the location, this on on the left D-pillar:
The speaker boxes :
Note: both boxes are not identical. Each had to be made separately.
The part used join these two rear pieces is actually very thick. In hind-sight, I should have used a metal bracket instead.
The speaker boxes are fixed to the D-pillar at two points :
1. The lower point is through a metal bracket, to the same point as the support for the rear seat's back rest
2. The upper mount point was trickier. A socket was already there in the frame of the body, but this needs an odd-size bolt. Tried in many places before my SA at my TASS came to my rescue with the crucial 11mm bolts:
It did take quite some time & patience to get the alignment right. Esp for things like size & alingment of the components of the boxes, the holes that needed to be drilled to precisely align with the mount points .. Doubt I could have got this kind of a setup done outside. Satya had even got a box done from his supplier, but that did not work out.
The speaker box mounted :
Note the box being held by the 11 mm bolt. And the metal bracket below.
The speaker box with the speaker:
And the end result of the effort :
While all this was being done, twp parts of the upgrade had been completed at the very begining : a GT5-604 & front components. Had added the amp trying to see if a sub could be avoided. Having the amp itself meant that adding a sub later was going to be that much easier.
The 4" co-axials on the dash have now been replaced by Boston S50's - 5.25" component speakers. Nice sounding set, kind of laid back, nothing harsh.
The 604 has been placed Below the middle seat : there's just enough space there for the amp, and for movement of air. And nicely out of the way too.
From the front of the Amp:
Routing of the wires has been done inside the body shell for most part.
And finally, adding some PUNCH :
The thought process continued to the sub-woofer too. The box had to be stow-able, to be placed in a way that it did not intrude much into passenger space at the back. Not that I have passengers in the truck, but the idea was to be prepared for any situation.
The requirements meant a small box. Meaning, a small sub. Had thought of a 8" bass tube, but none available in India.
Options for 8" subs I had were either RF or Polk Audio. I took the RF. Recommended volumes for a sealed box was upto 0.3 cu.ft. The box is 9" x 10.5" x 12" on the outside. Total internal volume inside works out to about 0.35 cu.ft.
This one is the smaller of the available subs, but it packs a sufficient punch of bass. Just right for what I was looking for.
Another change that was not intended was the HU. Was looking for the Kenwood 6039U for the Ikon, but when I went to get it fitted, found that it was not available. I had to either shift-down or move away from Kenwood, or go for the 6539. Ended up with the 6539 for the Ikon.
The 6539 has a different interface, something that I am not sure about giving to the hands of a driver ( the Ikon will be driven by a driver). Also additional features that made it more suitable to this set-up than the plain-jane HU-Component Front- Coax Rear setup that the Ikon has. So the one way out was to swap the HU's : and the 6539 ended up in the Sumo, while the Apline 9826 went to the Ikon.
Approx cost : 17k. All items through Satya, and most of the work at his place - apart from the obvious ones like the stuff done at home.
Another forced cost was 1.8k for the D-pillar panels which got damaged during prepartion. Plan was to use art-leather covering on top of the panels, but this didnot work & the panels also became un-usable. Had to get new panels from TASS
There is a sea change in the sound-stage now. It has taken time & effort, a lot of DIY, and a lot of Design-I-Y too. With generous help & inputs from fellow TBHP-ians. Talking to Satya, DerAlte & B&T has not made me an expert - they are way up there ... But I was able to learn a little more about ICE. And an ICE setup that I'm enjoying.
Thanks again: Satya, Aniruddha & Ajay ! And a mad Mullah & his Toyota.