Lol, thats the problem with purchasing car audio equipment soley off the internet.
Of course a sub/box combo is going to sound a lot different in a showroom than in a vehicle. I took back a pair of 10w6v2's for that very reason. My old 10w3's had better midbass transition.
There is nothing I hate more than going into a shops sound room and have the guy tell me, "they will sound way better in your truck." Oh god...and when they turn it up so all you can hear is distortion coming from the subs, then they say, "sounds good...dont it".