i have a box that was sealed and bass was unreal it was 143.4 dbs now that i put ports in it 2 x 4" x 12" i lost a few dbs..i was sure i would gain..as another member on here said that the tuning of the ports is a major factor..what is the right dimensions of the box i need and is a sloterd port better than what i have now for mostly dbs than sq..

might wanna put up the maximum size you have to work with, so others might be able to design something for ya..

i'm hopeless with ported boxes so im no help..

roughly the space available is 110cm l x 16cm h x 150cm w room in rear of wagon... the box is 110 x 34 x 60 atm divided by 2 cause of 2 subs

Dude, its not just a matter of throwing some ports into your sealed box, I'm not surprised it isn't as loud and most likely it probably sounds like a$$ now as well.

Some subs are suited better to sealed, some are suited better to ported. Most subs will go louder in THE CORRECT ported box, but that doesn't mean they will sound good or as good doing it. Some subs suit big boxes, some subs suit small boxes but generally a ported box will always need to be bigger than a sealed box for the same sub.
Post up the specs and someone might be able to model a box size for you, otherwise try searching, I'm sure these subs have been covered on here multiple times before.
Slot ported vs round/aero ported makes no difference to the sound. Its the size/dimensions of the port that are important.

kicker specs are
SEALED
.88 cuft, 24.9 ltrs min
2.0 cuft, 56.6 ltrs max
VENTED
1.75 cu ft, 49.6 ltrs min
3.25 cuft, 92.1 ltrs max
while i had sealed it ran 143.4 dbs

Try posting up the T/S specs of the sub.

Alternatively just build the largest ported box that Kicker recommends.

i may sound dumb but whats the T/S specs.. the biggest ported box size from kicker is 92.1 ltrs per sub..3.25 cuft

QTS, VAS, Fs etc.

SPECS FOR KICKER S12L7 solo-baric

nominal impedance[Zn],ohm[per coil] 2 or 4
resonance frequency [fs],Hz 34.0
power handling watts, peak (rms) 1500(750)
total Q-factor[Qts] .513
equivalent volume[vas],ft3(L) 2.2(62.5)
outer frame dimension, in(cm) 12 5/8 (32)
mounting depth, in(cm) 6 13/16 (17.3)

Urgh, we had a guy that did the same thing in a box for a single L7 and two CVR 12"s. Instead of any sort of porting, he just cut circular holes in the box and hoped for the best.
We ended up using Bassbox Pro to design an enclosure for the L7 (ditching the two 12"s) that was big - took up the whole rear of his Rodeo. It did 140.8dB @ 38Hz, a LOT louder than the three subs that had more power.
If you can tell me the area you have to work with, I can make you up plans for a nice ported box that should go pretty hard.

i have a commodore wagon(vn) so i have heaps of room to make a box for the 2 L7s..