Assuming that 600 dollars is your budget(based only on the price of the pulse sub(not) that crutchfield sells to accompany your soundbar), I would look here.
http://www.hsuresearch.com/products/vtf-2mk5.html
It’s much cheaper, and you could use the extra hundred bucks to buy the wireless deal that works with your soundbar. Not to mention it’s actually a real subwoofer, and will completely destroy the 6.5” pulse thing.
Of course you’re at Audioholics looking for subwoofer advice so I could also assume you looked at the pulse sub and lyao... If the latter, I apologize for even mentioning it.