pyrimid powers are worth the money

people say that pyramid is a sucky brand of subs but i bought two 8 inch 400 watt subs brand new from a webs sight for 13 bucks each and for the money those subs are great there loud as f**k but i dont know what the formula is to get the corect port size if each sub needs 1.8 cubic feet how much would you increase the box size by and what formula would need to get the formula!!! the rms is 250peak400and the freq is 38-to i dont know i have to check.please right back

If you contact Pyramid they should be able to provide you with the box and port specs. http://www.pyramidcaraudio.com/info/contacts.asp

But if you have the ported volume and the correct port frequency you can calculate the port using the 12volts port calculator https://www.the12volt.com/caraudio/boxcalcs.asp#por