Car Stereo

I have a 12 in kicker solo x 5000 watts and an ma audio 1800 watt and class x series in a home made box. it is in a ext cab truck on the seet. how many decibles should i be hitting . and i was wondering if it would be alot louder and a better sound quality if i had a car audio shop build me a box.

Take it to a radio shop it will sound better..