EMS Powered used to... they are no longer running their shop, from what I hear. I think there is a Doug Thorley Cat Back System too... found one on Amazon, probably elsewhere too.
Yeah, the Doug Thorley catback set works well with the headers. Sounds great but drones at highway rpm. I can't tell how much torque gain i got since I put them on at the same time as a TRD SC install. I think RobRed on the forum actually did a set of dyne runs testing stock, ems, and thorley.