guys,
the mini cats are part of the down pipe in 2000+ models. you can see it in your pic, the part before the 2 oval shaped flanges are your headers ( 2 piece ) and the tree shaped thing is the down pipe. you have mini cats on them, I dont, I just have the twin downpipe
http://www.flickr.com/photos/lwade/s...7627248416910/
so the way i see it the header has nothing to with it for 2000+ models.
As for the job itself there are 2 parts, dismantling and putting everything back together. In both cases the nightmare are those dreadful 4 bolts that hold both the intake and exhaust manifolds together.
Here are your options from my experience:
as gradon said, for dismantling you can reach with the tips of your fingers from the side of the intake manifold to seat a 14mm socket, you will then need a cv joint adapter on the socket and an extension. Thats how i did it. I didnt remove the downpipe. you'll swear a lot, but it can be done. and without removing the downpipe.
The real nightmare started when i had to install everything and found that the collectors on the flowdaddy are huge compared to the silly tree branch shaped oem manifold. I could not squeeze a finger between the header and the intake.
So I removed the down pipe, and spent 1 hr under the car with an open 14 mm wrench ( no way any socket will fit now ). and used a tube as an extension for the wrench.
One hell of a job, specially trying to seat the bolts in their threads using half a finger from underneath the car.
The final part of the nightmare was to torque down the flanges between the downpipe and the header, again zero clearance. I had to do it from the top of the car with one knee over the front fender and another on the front wheel

using 2 open wrenches.
As for the flowdaddy header, Its very well built, fit perfectly, and came with everything needed. It performed exactly as advertised, big improvement in torque below 3000rpm with a slight improvemnt in fuel consumption and mid throttle rpm completely eliminated.