Couple of questions for those that have done blow-throughs. This is the back seat in my Mitsubishi crew cab. If I were to mount my amp on the back of the seat (where the sub box is in the pic), would that restrict the air flow in to the cab when the seat is up?

Also, in regards to the tuning theory of building the sealed section, measuring peak and tuning the ported section accordingly - does that work with a blow through? I would have thought if the cut out is smaller than the overall cone area, then it would act as a really high tuned port?

if the seat is not back with hard plastic or metal then you're fine. 

It's just fabric of the back of the seat frame, but I want to mount the amp (SAZ-3000d) to it, so there would be a large hunk of aluminum fairly close to the port mouth.

Anything close to that port will take some serious abuse.

If you plan to install a "Blow Through" enclosure in your bed, and you plan to go through all of the trouble to cut your truck's body, you would not want to build an amplifier rack onto your back seat. In fact, it would be good to modify your back seat to where less material on that back seat, the better.

You would be best to install your amplifiers either under your rear seat or in your bed along with your sub enclsure.

Also, if you plan to install your enlosure in the bed of your truck ?? Do you have a fiberglass bed cover or something similar to protect it ???

if you have to install the amp back there, i would think about cutting the hole for the blow thru on the driverside and install the amp towards the passenger side. 

There's no room under the back seat. These trucks have a raised floor in the back to make room for the gas tank.

Would prefer not to put the amp in the bed. I'm in New Zealand, where we have an almost sub-tropical climate so I'd like to keep it as sheltered from the elements as possible, not to mention would-be thieves. I'll be making the box using treated timber and have a tonneau cover over the bed.

Believe me, I've thought a LOT about all the options.

One thing you could do is (to do a blow through, you would have to do this anyways) build a solid baffle on the back wall. That way you could reinforce the cab and build and amp rack at the same time. Then you can build your Blow through mouth opening in the center of the baffle with an amplifier(s) on each side. Having a small truck, this will be tricky but should turn out OK with the least amount of vibration for the amplifiers. If your amplifiers are mounted to your back seat, Jay-C76 said it best as to what would happen.

 

I'm in New Zealand, where we have an almost sub-tropical climate so I'd like to keep it as sheltered from the elements as possible, not to mention would-be thieves. I'll be making the box using treated timber and have a tonneau cover over the bed.

Believe me, I've thought a LOT about all the options.

Treated timber is not going to help you Sir. You would need to atleast Line-X your enclosure / mouth opening to prevent water intrusion. Trust me, It finds a way.

Bad part about Line-X (when done correctly) is once it's done, It's very hard to get back in there for maintenance.

If possible, a fiberglass cover is the best way. Even then you still have to work at keeping water out.

Another option is to remove th rear seat entirely and have the enclosure half in the cab and half in the bed. That would give you room on top like a shelf to mount an amp rack.

Or wall the cab and forget the blowthrough

One thing you could do is (to do a blow through, you would have to do this anyways) build a solid baffle on the back wall. That way you could reinforce the cab and build and amp rack at the same time. Then you can build your Blow through mouth opening in the center of the baffle with an amplifier(s) on each side. Having a small truck, this will be tricky but should turn out OK with the least amount of vibration for the amplifiers. If your amplifiers are mounted to your back seat, Jay-C76 said it best as to what would happen.

 

That's not really going to work either. I'm running a Sundown SAZ-3000d on four 12's, and want as much port area as I can get. The Sundown would take up over half of the available area. I'm starting to think roof mount may be the only way to go without too much compromise. The only trouble there is running four runs of 1/0 gauge up the C-pillar and keeping it tidy.

Another option is to remove th rear seat entirely and have the enclosure half in the cab and half in the bed. That would give you room on top like a shelf to mount an amp rack.

 

 

Or wall the cab and forget the blowthrough

 

The reason behind the blow through is so I can keep all the seating.