Alright so i posted this on an other forum but no one really had any good insignt into what they think caused the tunning of my box become so high from what I tunned it to.

Alright here where Im at this is what the box looks like inside its ruffly a little over 7sq ft each side , port is 17.5 inches tall and 6" wide lenght wise its 19" then it L's with the smaller side 8.5" for a total lenght of about 28". So i was thinking i was going to be tuned to about 34hz well after I got metered turns out im at 57hz any idea where I fucked up?

and i know some people are going to say its just where the cab peeks at but ,This is the second box Ive ran in this truck. The first box i had tunned to 34hz and it peeked in the cab at 35hz which is where im trying to get back to. Old box was tunned with aero ports so tunning was alot eazyer

^^ yea thats what i was going to say..

but u can always do it like a wall build and just keep making the port smaller till you get it where u want it, if you have a meter readily available that is.

I plugged your numbers into BBP6, assuming they are correct, you should be close to 34 hz.

With the H/W dimensions you've provided the port should be ~29" long.

Do you loose control of the cone much below 57 hz.?

If you don't I'd assume the enclosure is tuned close to where you wanted it to be.

Turn the sub/infrasonic filter off, don't go nuts with the volume, and play some tones. Where does the cone move the least and where does the cone really start to move.

This could be a good indication of where your tuning really is.

If you want to verify your tuning, get an impedance graph. Grab a WT3 from PE if you need a way to generate one.

Trying to guess tuning based off of "peaking" inside of a vehicle is useless endeavor.

Was the last enclosure a blow through? If it wasn't, that's probably the reason for your new peak.