We've found reports spread across SEAT, Volkswagen and Audi forums which show the brand new Golf R, Leon Cupra and S3 have developed this. Most reports we've been able to find are about the Audi S3, which is probably because the S3 has more variants and went on sale earlier than the Golf R.
All three models come with a 2-liter TSI/TFSI making either 280 PS or 300 PS (engine code CJXB, CJXC). The part at fault has the code "06K 145 702 N" and from what we gather is made by IHI Turbo (formerly known as Ishikawajima-Harima Heavy Industries).
All three cars are based on the same platform, the MQB, which means the mounting points for their engines are the same and so is the distance between the firewall and front axle. However, there are some differences in the powertrain. Both the Golf R (Type 5G), and the S3 (8V) have all-whee drive, while the Leon has front-wheel drive and 20 PS less.
According to one of our sources, the problem lies with a small batch of turbochargers that were built some time this spring (April and May), but a few owners have been reporting breakdown on the 2013 S3. The problem is repeatedly being traced back to the manifold sealing surface. This could be why Audi is rumored to fit a brand new turbo design on 2015 model year S3 and pushed back the launch of the TTS compared to the normal TT coupe.