This month we're working on a specialized vehicle, but the project applies to many different cars. One of our clients has a full-sized GM van that he uses for business. His business involves sound, so it's important that he has a good-sounding system in his vehicle. Unfortunately, the GM van's factory speaker locations are by his ankles, very low in the doors and very poor for good sound quality. The best solution here was to mount his primary 4" Alpine Type X separates in the A-pillars of the van, much closer to his ears. The factory speaker locations were used for 6 1/2" Alpine Type X midbass drivers, creating a three-way system. Many vehicles have pillars similar in size to the van, so check to see if you can do a three-way system like this in your vehicle. Send questions to sbrown@alpine-usa.com and check out SteveBrownUniversity.com for more information.
The first step when working with any factory plastic pieces is to rough them up to promote adhesion. | 
Holes are cut in the factory A-pillar panels to mount the speaker rings. | 
The Alpine Type X speakers were used to mount the speakers in the pillar. |
Next, the speaker rings need to connect to the plastic pillars. | 
Curved areas like this require several pieces of cardboard to create the complex shape. | 
The insides of the speaker rings need to be taped off to avoid fiberglass resin from seeping inside. |
Three or four layers of fiberglass mat and resin are brushed over the cardboard. | 
After a few hours, the fiberglass can be smoothed out using an angle grinder and a 36-grit sanding disc. | 
Rage Gold body filler is applied to the fiberglassed areas. |
Thirty-six-grit sandpaper is used to smooth out the filler. | 
Polyester primer can now be sprayed on the entire pillar. | 
After applying three to four layers of polyester primer, the pillars are allowed to dry for several hours. |
The pillars are sanded with 120-grit sandpaper to smooth out the primer. | 
Many installers like to spray a second coat of polyester primer at this time, but I like to use NCP-280, a PPG primer. | 
Two or three wet coats of NCP-280 are sprayed on the pillars, with about 10 minutes of drying time between coats. |
The NCP is best sanded wet, using wet-type 400-grit sandpaper. | 
Three semi-wet coats give a nice finish with a slight texture. | 
The pillars can now be installed. The factory attachment points were retained and an additional bracket was added behind the midrange for extra support. |