Just to make it clear, I'm not bagging on this kit or trying to bad mouth it in any way. My comment, regarding the potential of a cracked header comes from my own observation of my original factory header in a bone stock application. Mind you, I had no idea that a crack was present in the header until I removed them during the cylinder head swap to the Striker heads.
Stainless steel's coefficient of expansion is much greater than mild steel, essentially it grows more than common steels as temperature changes occur. The factory header is probably (I'm not certain of this) 409 grade stainless. It is a commonly used stainless steel by the OEM's. It's great for most exhaust applications but is at the bottom of the totem pole in terms of quality stainless steel. The next best choice which is commonly used by the aftermarket is 304, Corsa is an example as well as Borla exhaust's. The best choice for ultra high temp applications and undisputed by any engineer is 321 Stainless (their are better choices but they cost big money, Monel). 321 is the obvious choice for turbo charged applications, as it can withstand the extreme temperature cycling that occurs in a turbocharged application. Some of you with a keen eye may have noticed that most OEM's use a cast exhaust manifold for turbocharged applications. Quality castings tend to be more stable in their overall rate of expansion. Additionally you'll note that piping will be installed with a flexible joint, which allows expansion without the transfer of stress downsteam.
Again just to restate what I've stated before, I think that this kit looks like a great design, specifically at such a resonable price point. That said I would stock up on factory exhaust manifolds if your going to run it hard like it was designed to be run. As a side note, I've been into metals and welding for most of my life, it's a passion of mine. Back to the regularly scheduled program...............That car is going to boost the stock of whatever tire company you choose.
