If you have an Eclipse GS-T or GSX, it will easily be faster than your teg, but not as reliable (depending on condition.) You can put down good numbers with a turbo Eclipse for pretty cheap.
If you've just got a base model Eclipse, mod your GSR. However, It will cost a lot to get the GSR into the 12's. I think the GSR looks a little better overall, but Eclipses can look very aggressive with a nice drop and good wheels.