I may need to replace the set on my car and the rest of the exhaust is junk. There seem to be only two manufacturers of headers on the Australian market. Both use a 1.5" primary of approximately the same length, but the difference is in the collector. The Hurricane use a 1.7"/44mm secondary and the Pacemaker use a 2.5"/63.5mm collector. Given each bank is only 1500cc the Pacemaker seems huge in the collector. What are people's experiences with these headers with a stock, mildly or heavily modified engine? What size pipe is used for the main ex system? 2"?

Fitted a set of Pacemakers to a stock GTV6 manual. The rest of the exhaust was 1-3/4 (i think) as it was a twin system. Mate is very happy with the sound and performance. I have always used pacemaker extractors for my Escorts.
 
Cheers, Craig.

I went with the Pacemaker headers ( kept my original headers in storage)
They are a perfect fit.
 
Here is a quick pic of my exhaust (Note it doesn't have a balance pipe, it just has a support welded between each pipe to prevent rattles etc)
I decided to delete the rear muffler to give it a bit of a note and its perfect not to loud and not to quite.
 
I also went with flange fits for all the connections so if I have to remove it is super easy.
 
 

Thanks for the feedback, very helpful. 1.75" or 2" seems the correct sizing, I think 1.75" is on there. Interesting to see two pipes one side - this car has one either side.

I put the pacemakers on mine, with balance pipe, the biggest triple chamber mufflers they could fit, and a rear resonator on each side behind the diff.  Its 2in up to the mufflers then back down to 1.75 to get some back pressure back.  I hate it, way too loud and the engine is just stock with a mild cam.  My old system which was all 1.75 had a nice note at idle and then quietened down at cruise.  That said it should get a bit better once it carbons up a bit more but if I had my time again I wouldn't go 2inch.  I also wonder what the will thickness difference is as the noise seems to ring out of the pipe work.  No noticeable difference in power.  I kept my old ones and will be changing back when I strip for the respray.

current pipes are 1.75".