Apexi N1 model diff. for GS vs. GST

Apexi N1's are listed for a GST, GS, as well as a GSX. Now I know that the AWD cat-back is different in that it runs under the axle where FWD have the tubing going over the cross member.

Question for those that know: what is the difference between 162-KM01 (GS model) and 161-KM02 (GST model)? The OEM section from the Catalytic Converter back is identical for non-turbo and GST, save that the GST muffler is higher flowing. OEM Flanges and exhaust hangers are the same. Is the GST model made by Apexi a larger diameter pipe than the one listed for non-turbos?

I have emailed distributors regarding this but have not received any responses.

Any insight into this is greatly appreciated.

I am pretty sure the gs model is 2.5" and the gst is a 3"

*bump*

Any other solid info on this Question?
(Thanks for the info though ashah)