I got my only 1.6 60ft with the lopro cover and tailgate on.
With the cover and tailgate off,my mph went up but et suffered slightly.

 

It depends on your mods. If you are running F1's and no traction devices, I ran better with the extra weight in the rear. Even stock.

If you have Slicks / ET Streets and a traction control device, go light.

 

i was running hoosier street slicks and ran SLOWER when i took spare off,i guess the extra 60# behind the axle actually helps out with traction,might even increase in weight when the rear end squats(launch) just my $.05