i did EGR last night,
i used 5mm Ally plate that i cut and grinded down, i think using ally works better as its a softer metal and will seal better... make sure you do ur VAC lines as well...
because of other issues with my rig i havent seen a benifit yet but have seen with a mates car certainly a mod worth doing, but on a stock exhaust system be sure to keep an eye on EGT... i have 3" exhaust so not going to cause any problems.