Mate got a set of JBL 1 Series 104BT for xmas, do the job nicely, although I am JBL fan in general 

A question, does a sub add anything to sim racing. Just wondering as I have a sub out on the 1280dbs.
i have no idea about its affect in Sim racing, but a SUB if the best and only way to get the real low tones and the rumble from the sound.
if i had one it would be in use
Definitely, I tried out Imax super speedway, the race scenes where the car goes over the bumps you actually feel that.
Although having two 15" subwoofers in a PC system is probably a bit OTT.