Cat amongst the pigeons.
In the end of the day, some people had problems with xs in the past so everyone jumped on the band wagon.
As craig has already said the track car is driven hard all the time an no problems have occurred with this phantom cracking manifold. 8k to do a proper n/a-t conversion is quite funny as well. Craigs car has cost him under less than half of that, the car does not miss a beat, and running up around 400 bhp. So does this sound like their parts are crap, or more than likely one person having a problem and then it growing into a Chinese whisper to the point where you get warned to stay clear of it.
If you are on a tight budget then the kit will do the job that it is need to do. Just use some different oil lines as they are the only let down to the kit tbh.