I would recommend MB Quart. Infinity Kappas are cheap junk, they sound decent at best for the first 2 weeks, then they sound like sh*t and have a tendancy to break. Depending if you're looking for 2-way or 3-way 6X9's CBRStereo.com has both set's of MB Quart's at very low prices.

MB Quart DKC 169 6x9" 2-way

MB Quart DTC 169 6x9" 3-way