Gerald said that Gude kit is garbage. A quick search on here brings up the same conclusion that it's junk.
Idk what the specific problem was for sure. From the quick reading I did it seems like the wastegate and no tuning were the issues though.
It seems cheap enough to purchase and replace the junk and have it custom tuned. Especially if it's still running now someone had to have changed a few things to keep it running since the Focus' early days.