I built a box a while back (2.25 cubes) and had it tuned to about 28 hz. Today I decided to tune higher, and went with 32. I cut my aeroport down about 4 inches and drove around for a while. I absolutely hated it. The SQ went out the window. IMO, this sub should not be tuned higher than 30 unless you are not an SQ fan. I bought some PVC and extended the original length a tad, making the tuning frequency 26hz now. Sounds 1,000,000x better than @ 32hz. It's possible the size has more to do with it, but I dunno.... This is all just an opinion though. Hopefully some people will see this when searching for what to tune this sub to.