2011 Pathfinders 4.0V6 engine asking "premium gas recommneded for maximum performance"; I added regular gas once and felt something missing in the performance; then I changed back to premium and it felt OK again. You could be talking about a v8 version thouhg. In my case it might be the KNOCKING when regular unleaded feul is used and while a higher power output is demanded. Just some thoughts....
btw, your TURBO mentioning shocked me. i'm from usa and where r u from?