Been there - living the misery! I had the cracked B20E manifold and did the tour of the welding shops trying to find someone to fix it. Most of the shops turned me down flat because of the material (cast iron) and the location of the fracture. A couple offered to try; but, wanted payment up front with no guarantee of the results - particularly the all critical dimensional stability.

More out of convenience, I ended up with the Patriot / IPD header. The header may or may not alter performance. However, the fit was poor requiring modification of my intake manifold to eliminate interference with the flange. In addition, when I was modifying the flange to get a reasonable port match, I discovered that when the #1 pipe was 'squashed' to get a square shape to match the B20 ports, the tube seam had split requiring that I get the seam welded up (the header is not fabricated from seamless tubing). I am waiting for that seam to eventually open up again. The spigot provided with the header does not match up to the diameter of the stock B20E exhaust system. The header hangs below the transmission exhaust bracket by about 25 mm so you need to modify that hangar. The transmission bracket is important. You end up with a lot of rattles if you try to get by without that bracket - I tried! So, short story is give the IPD header a miss unless your are really desperate.

My manifold ended up in the garbage. Knowing what I know now, I wish I had used it as a template to create flanges for the down pipe and head surfaces and then used those to have a tubular version created of the original manifold allowing me to retain the stock double down pipe.