Yeah poor choice of words, sorry... the larger turbine wheel in the housing specifically designed for a smaller size can lead to issues with high cycle fatigue and lowers turbine efficiency, but I know, it is an easy upgrade.
T3/T4's are not similar to the lnf upgrade turbos in that the housing and wheels have been designed together on those. Just because there are a lot of something being sold doesn't make it good, either.
Sorry, no proof of EFRs except that I work 100 yards from the production line.
07 Solstice GXP
Hankook/ Koni/ Solo Perf./ Zok bars