I know I don't drive a Leon but I noticed this post and thought I'd reply. I was at a vag meet the other week and apparently you can run an atmospheric dv on a 1.8T, just not on the vag ecu. The guy was running a DTA ecu on an audi tt 225 engine in a mk 2 golf. Whether having a whooshy sound is worth £600-800 for an ecu is a matter of opinion. Personally I don't think it's worth it but hey, just my 2 cents.