Originally Posted by Team_STILLEN

1slow370 is correct. The stock cats will last longer than HFC's and are also more durable. They are very unlikely to break apart. We have seen HFC's blow out and clog the exhaust. I would not be concerned with the stock cats breaking up and sending pieces into the engine. The exhaust gases are coming out so fast I don't even know if that would be possible.

You are going to lose almost 1 lb of boost in the actual cylinder from using test pipes so you'd probably get back 20 whp from going back to stock cats (though I see you are on an upgraded blower which we have not tested). There is a chance with the upgraded blower the boost would be too high in the cylinders but I couldn't not say without testing.

@Nism0 If you are piecing parts together for the kit, might as well go with some 725-750cc injectors.