I recently got a stage 1 apr tune, and a 2009 CC, and the car was pulling great until I blew something. I got CELs for p0101 (maf sensor), p0172 (system too rich bank 1) and p0299 (underboost). I also got a high pitched whistle when I called for a lot of boost. Figured it was the diverter valve, so I replaced that, which did nothing. Next, I replaced the PCV valve, which got rid of the p0299 underboost code, but I still have a whistle, a noticeable lack of boost (especially at higher rpm), and codes p0101 and p0172. I tried cleaning my MAF sensor and taking apart my cold air intake and putting it back together, but the problem persists.
Any ideas guys? Im thinking that I have a vacuum leak and that I might have to take it to the dealership to get smoke tested. Also, are there any components which are especially prone to failure after stage 1 software? Any guidance would be greatly appreciated