tuning

[jizazz12]

Ok, box is built subs are in and sound nice but I have another question psp port calc calls for my port length to be 18.27 which I went ahead and cut a 1.27 ring of 6" tube to extend the tube in the kit out to get the 18.27 the calc is telling me I need but it seems as though the box is tuned a little high.

If I take the 1.27" ring out of the equation and just use the 17" of port that come with the kit would I be lowering or raising the tuning of my box? I'm getting ready to swap out my m1 lvl3 to my xlm2's and was wondering if while I'm in there I should leave as is or adjust the port to get the box to hit the lower frequencies a little better, it's plying down into the mid 20's now but is seeing a drastic roll off rite at 30 htz I used a test tone sweep to see where i was at, seems to be peeking rite at 45 htz, after 30 the lows are there but not very pronounced.