You have an Xp cam, E85 and are running a 2.8 and only ran a 13.3? Driver mod? Post your slip if possible cause i'm wondering what your 60 ft was.
Maybe a good set of slicks can get you close to 12's.
I should probably update my sig that im driving a 4000 pound buick and not a GTP.. 60' was a 2.01
1999 Buick Riviera - L67
PLX wideband +HPT pro +X-P HOT cam, 140#springs, 2x chain, LS7 lifted
ZZP SS Headers + 3" Downpipe + 200 Cell Cat.+ Aero Resonator
Gen V swapped L67, 60# injectors, E85, N*&LQ4MAF