need dimensions on a box for a 15 fi sp4. website says 3,5 cu ft but other people are saying go 4 cu ft. really would appricate it

how much room do you have to work with? what are you running to it? the sp4 will move a lot of air so port area needs to be right

For someone to be able to design you a box you first need to list the dimensions of the max area you're able to give up in your vehicle, for obvious reasons.

im running an sp4 15 on an saz-1500. from what i read big power = smaller box andl low power = small box. fi says between 3.5-5 ft^3. mine is in 4ft^3 after displacements w/ a slot port tuned at 33hz. my problem is my electrical its all stock other than big three. i pulled a 140.2 on music sealed on the dash, sub firing into the car not sealed off, had amp gain dialed back due to failing alternator at the time.

 

since then ive got a new alternator and battery but still stock, tuned the amp back up, and have the sub firing into the trunk which made it a completely different animal. its louder, lower, and tearing shit apart. 

 

post up some measurements of available space and ill get you measurments of my box tomorrow