ok. you CAN still get the DC headers if you want. they're the best headers for the money in my opinion. BUT if you want to weld in a hi-flow cat, you're going to have to cut a piece of the downpipe off, and weld the cat on...
why would you not want to do that with the DCs? they're ceramic coated, so you have to cut through that, adn then weld a stainless steel cat onto the ceramic coated steel.
If you look at the little diagram thing i drew, it shows that the DCs have the collectors (two things with the 3 pipes coming together) and one long pipe that joins the 2 collectors. That long pipe is the down pipe. That will connect to the mid-pipe from your exhaust (cat-back or stock).
the SSA headers (and other similar brands) have the 2 collectors, that join to one downpipe (exactly like the DC headers), except the downpipe is shorter, and it bolts onto another pipe, which THEN bolts onto the exhaust mid-pipe. That intermediary pipe is called a "test pipe" or a "race cat"... it's just a hollow pipe.
THIS system is better if you want to weld on a hi-flow cat because you can just take that intermediary pipe, cut off the edges, weld that onto the hi-flow cat (which is a pipe with a honey-comb like interior), and then just bolt it back onto the exhaust... That way you won't be cutting the downpipe, or welding the cat directly to the downpipe...
understand?
pics. would help... go to ebay.com and type in "DC headers Tiburon"... they should have a set on sale, and that's the only place that i found an accurate picture of the headers (other places picture a random 4-2-1 set for some honda or other application). Then search "SSA headers Tiburon", or just "headers Tiburon", and look for SSAutochrome... there you will see the shorter downpipe, and test pipe.
oh, and the best place to buy DC headers is from kjbmotors.com. $425 shipped. Ptuning.com also has them.
best place to buy SSAs are on E-bay... i think they're around $290 shipped.
Keep the installation in mind. it will be expensive if you don't do it yourself or with a friend!!
....