I understand im getting cancellation from my boot, as the boot isnt sealed off from the cabin and therefore one sub is firing into the cabin while the other is going into the back seat and remaining in the boot. Buut what i dont understand, why would rear loading eliminate cancellation?

Rear loading both subs fire in phase and the sound hit the boot lid, and refects, When they reflect the sound is still in phase. The pressure then goes into the cabin in phase.

When firing forward say 60% of the bass goes forward and 40% goes backwards. The sound going back then reflects off the boot and comes forward again. When it comes forward it will be delayed and not in phase with the sound wave going forward.

why does the sound go 60% forward, 40% backward when facing the sub forward..but ur saying when u rear load the subs this doesn't happen..

why does all the sound go forward then hit the boot etc..
i dont understand?

Here is an interesting link to have a look at Rick. This is why we've been trying different positions for the enclosure in your car.

Aiming subs article.

yeh i am a bit sus on this too as i just changed to rear loading and it sounds heaps worse i am getting a crap reverb cancellation that is crapting me.

When people refer to cancellation in this context, they actually just mean less cabin gain at a particular frequency. The sound does not totally cancel.
Facing to the rear does minimise this, because the sound that travels forward without bouncing off the rear of the car will be more in phase with the sound that does bounce off the rear of the car. In the case of facing forward, some of the sound will bounce off the rear of the car and will be less in phase. (as compared to rear loading)

There are downsides to rear loading:
(1) Increased rattles.
(2) If the box is too close to the rear of the car, or the box practically walls off the rear of the car from the cabin, then this will introduce problems of their own.

Rear loading doesn't actually add any audible delay per say (due to the long wavelengths), so if rear loading sounds "slower" it is due to an altering of the frequency response - perhaps less midbass. This problem will be emphasised if the box is too close to the rear, or the box practically walls off the boot from the cabin.

If facing foward still allows you to obtain a smooth frequency response, then there is no need to rear load. (unless you need the increase in SPL for competition...)

Just to continue on what Bassaholic said, consider this:

The sound waves only ever truely cancel each other out for a fraction of a moment because at any particular given frequncy they only reflect each other perfectly for a second (so far as length is concerned) because music is ever changing.

One other thing; if you mount the subwoofer too close to the rear you can cause loading on the front of the cone. Similar to a bandpass enclosures, the lack of airspace can resrict (however marginal) the front of the cone.

Well the restriction of the cone itself isn't neccesarily a problem, the real problem is the effect on the frequency response - if it is too close, the frequency response may not be as smooth and the midbass will be filtered out somewhat...

That's right. The minimal extra load is very unlikely to effect the cone itself, it could just influence the sound reproduction a little.

Try it and see! :D