Back when the 99 cobras were a year old and people started making longtube headers for them, it was discovered that MAC longtubes were causing the destruction of every cobra engine they were bolted onto. Within 100 miles, the engine would be sucking up a quart every 50 miles, smoking like a train, and when torn down, the damage was always the same...scored cylinder walls, cracked ringlands, rings wiped out, exhaust valve guides/seals wiped out, etc. No one could understand why this was happening. I had a theory that turned out to be the problem. During engine braking, a high intake manifold vacuum is created. Valve overlap allows the exhaust to suck right through (and the EGR valve being open), the weld slag was being sucked right out of the primaries, into the cylinders, and all the way to the plenum of the intake manifold. The quality was HORRIBLE. These headers, new, were FILLED with slag, big weld stick remnants and tons of abrasive material....most likely all the grinding tables and wheels. They werent putting any effort into cleaning the headers properly (for some reason just the cobra header line) and this crap was sucking into cylinders and destroying engines. I had a little challenge, (people had alot of different ideas as to what was doing it) that if I were to buy a used set of MAC longtubes, that had already trashed an engine (all the crap already got sucked out of the headers), and stick them on my car, that my engine would be fine. I found a set that were filled with carbon because the engine they came off of had been destroyed and it was consuming major oil. I put them on my car (12 hour installation), and my engine was never damaged.
Anyway, putting headers on an engine that are filled with slag is a major risk. Especially when those primaries are ending up going through a TURBINE. I welded up a crack on my headers, and didnt clean out the slag...just flushed it, but I couldnt get in there and hammer every bit of the crap out...1000 miles later, the thrust bearings in my turbo are shot. And thats just from welding up a crack, let alone all the slag from an entire set of headers.
Be careful people!
But, these headers look like diamonds compared to that MAC garbage. After seeing these ones, I doubt they'd do any damage. Im pretty stumped by how they can afford to charge 300 for these things. They're beautiful! Oh yeah...when workers make 1-2 dollars a day, thats how.....