Thanks mate, made a new design which doesn't have ports. I'll be posting all the pictures of the box on my cars page here

Nowories man i'd rather you build it right first time round than have to redo it later like i've had to do over the years.

this is the new design i made

Ignore what the height says in the photo I've redone it and its 350mm high, 800mm wide and 350mm long at its longest. but overall the same shape

Cool design, forgot one thing make sure to baffle down the middle creating two separate chambers this way they work independently of each other.

not exactly sure what you mean by that? do you mean close up the box in the centre so the two subs have they're own box within the box? sorry for the terrible example

Exactly

Well I had it open because it would be enough internal volume for the subs, I know there is something you can put inside the box to help with the internal volume but I cant remember what it is

you need to put a seal between the 2 subs or what happens is the air that is pushed inwards to the sub box will make its way around to the other sub & push it out slightly making shitty noises & double beatin

go look at the manufacturers website for volume specifications to make sure the sub enclosure is big enough

you normally fill the boxes up with abit of foam (textile foam from memory its normally white & woven)

The baffle between the two subs is VERY IMPORTANT and HAS to be their, the white stuff your talking about is only used if the box is a little too big and you want to bring the internal volume down in size and doesnt have to be used. Its also used for fibregalss enclosures which can sound flat at times the fill helps with the "solid" sound.

Once again I've changed my plans, Will just buy some sony 4" speakers that fit in the standard holes, is it worth getting 6x9's for the back as well, dont want anything fancy in this car my supercalifragilisticexpialidocious speaker system will go into my daily. might even run 6x9's alone, i honestly dont mind about quality as long as it sounds like the song thats playing

Well do you wanna run amps aswell or just front and rear speakers running off the headunit? you can still keep it simple and not spend alot, i'd go 4inch fronts (to fit in standard spot) 6x9s in the rear (mounted in small boxs) all running off a 4channel amp, dont use sony, this setup can be done cheaply enough without buying cheap brand gear, try Alpine type s series, i put a set of 6inch coaxils and 6x9s in mums laser for her running off a small 4channel and it sounds surprisingly good without spending shit loads bought it all as a "pack" from JB HiFi.

i was lead to belive that this is the other way around, you use a dmapening agent if your box is too small, it will give the sub the impression the box is bigger by delaying the air from bouncing of the rear wall/s of the enclosure, i used to use a simple block of timber to bring the volume of the box down.

the centre baffle is important, it will sound crap and lessen the lifespan of the subs, it also pays to hav either the sub or the rear of the enclosure on an angle, the air moved from the sub will bounce around in the enclosure rather than just hitting the back of the enclosure and then bouncing straight back into the rear of the sub (there is a lengthy scientific version but this is easeir to understand, even a simple abgled baffle in the box will siffice.

good luck with the system

krem