stock gsr's run at 14's...... what would be some good choices of turbos to put on to get it running 13's...

the greedy package for the gsr shoud get you into the 13's it uses a small td-05 i believe..
i say use any small turbo that spools up quickly.. a t-25 is also pretty good..

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T25 sounds good t28 would also be cool.

just so ya know stock gsr's run in the 15's... personally I'd say go with a t3/t34...

Yeah no GSR is going to get 14's stock.
Anyway, a T3 with a .48 A/R Turbine and a .60 compressor will do great.