Granted I have a Trans Am so it's not exactly the same but my car,at 3,550lbs with 3.08 gears on 26x11.5x16 ET Streets (mounted on stock 16x8 GTA wheels) my 60fts are usually in the 1.49-1.51 range with ET's around 10.7-10.8.My best was a 1.47 on a 10.69 run.
I think that though you may be heavier than me you are probrobly still running 3.42 gears and a 2004R trans(2.74 1st to my TH400's 2.48 1st), should 60ft at least as well as me.
Maybe a little more info on your combo and driving style,like how much boost are you launching with,can determine if it's the tires,suspension,or something else.
Thats my opionion if it helps any,
Steve