your turbo most likely has a bigger pitch and A/R on the turbine housing. gasser turbos usually have bigger specs, because they use more rpms to spool the turbo. the low pressure turbo on my car is off of a 2.5 l chrystler lebaron or something. its physically the same turbo as a VW t3, it has a bigger exhaust housing on it tho, and it has an A/R of 48, versus the stock 36 A/R of a VW diesel T3.