chevy impala lt 2007 heavy metal box

[ylpkm]

My friend overseas has requested that I do the install in his vehicle as the local shops (which truly arent good) wanted to charge him a minimum of $600 for a 300 watt amp and a 10 inch "Keeker" sub in a prefab box.
He wants to be loud but be able to hit the double bass kicks. He says he doesnt listen to rap or techno. So I was thinking of just putting in a 12 or 15 back there and just designing a box with as low of a group delay as possible. Since he doesnt listen to anything too low, should I go bandpass? Tuning would be fine around 45 hz right. He wanted to stay under a grand for everything, which i will still need him to encompass what everything pertains to.
I'm not posting a specific sub (yet) because the box is the bigger factor. would i just try to have the lowest group delay. And would i search for a certain amp, some having a faster filter than others or did i mis-skim the articles. When doing work for something i havent had to deal with (or really care as i wanted low and loud) I'd rather ask a **** ton of question than go in with no knowledge. The impala also has the trunk sealed off, i mentioned to him that it might help if we tore it out and fiberglassed it if he wanted to go big, but he wants to start small... (welcome to his new addiction)

[profundus-sanus]

you want group delay low in your passband, which sealed, high tuned 4th order, or low tuned ported are your options for that.