A boost gauge and Double DIN headunit were something I had in mind for a while, and finally got around to it. I wasn’t a fan of A-pillar mounted gauges, they looked too out of place and not as clean. Re-Amemiya had a boost gauge with a mount that goes above the steering column, so I ordered one from RHDJapan. I got tired of not knowing how much psi the car was boosting, so I always had to baby it as a precautionary measure. The electronic readout on the Apex’i Commander was shown in the millimeter of mercury and had a delay, so it wasn’t useful… had to have a direct gauge for boost.

The Pioneer AVH-P4200DVD headunit definitely updated the interior. I did my research on various double DIN units, and concluded that I didn’t need a lot of fancy features like navigation in this car, just something with good usability and touchscreen. I decided to wait on the P4200 which just released in March, 2010 and I’m glad I did. It has a handy SD card slot, too.

I didn’t feel like it was necessary to change out all the speakers. I personally loved the way the Bose speakers sounded and they worked great. In order to adapt to the Bose system, I had to get a special wiring harness from Scosche. Wiring and soldering everything up was straightforward, except for some dumb reason the Power Antenna/Amp Turn-On wire was in the completely wrong pin slot on the harness (blue/white wire). The pin it was in lead to an empty slot on the car’s harness, and was on the wrong connector all together.

Luckily there was this handy diagram I could resort to, and it was a matter of taking out the blue/white wire from the connector, and placing it in location 1J.

Completed wiring harness…

The installation of the boost gauge and headunit coincided well, so I was able to do them simultaneously. Right off the bat I was faced with a disenchanting obstacle. I had to remove the trim surround around the gauge cluster in order to release the trim around the headunit… all I can say is that trim piece was a major pain to get loose. There were 2 screws on the bottom, and the rest of it was held on by clips that might as well have been cemented to the dash. This required battling at a breaking threshold constantly, with the weak plastic a moment away from completely splitting in 2. That, and there was almost no where to grab on.

Perseverance prevailed, luckily, and it eventually came loose. Here’s a picture with the main trim pieces uninstalled, it looks like some carnage swept through the interior:

Using some removal tools and getting ready to pull the old junk out. The CD player never worked properly for me, and the Bose unit was plain. Since I hate the radio, I ended up using a cassette tape with an auxiliary input to my iPod… felt ghetto. Electronics such as these need to advance with technology.

Almost there… checking things over and setting the gain settings on the Scosche harness before locking things in.

Installed:

With the headunit taken care of, it was time to focus on the boost gauge and finish up. Coincidentally enough, Mazda left a nipple on the UIM capped off that was perfect for tapping into with the boost vacuum line. I ran the hose across the firewall down into the driver side’s fender. After pulling back the fender liners, there’s this plug that offered a clean entrance into the cabin. Using a straightened coat hanger, I fed it through and it appeared near the dead pedal.

Here’s the plug drilled to accomadate the hose:

Installed… unfortunately the column pod was designed for RHD cars and it doesn’t fit that great, I’ll have to take care of that later: