It's a trade off that I can't fully explain and don't completely understand.
SVT #1
15 lb wheels
stereo in rear
vs
SVT #2
25 lb wheels
no stereo
Stock wheels = 20 lbs (for arguements sake)
According to wavrdr's formula of:
1 lb of rotational mass lost equals approximately 8lbs of dead weight
SVT #1
lost 160 lbs of dead weight over stock
SVT #2
added 160 lbs of dead weight
SVT #1 = -160 lbs over stock
SVT #2 = +160 lbs over stock
Throw in a stereo for SVT #1 that weighs 100lbs.
SVT #1 = -60 lbs over stock
SVT #2 = +160 lbs over stock
Plus, SVT #1 should accelerate faster and handle better assuming equal driver.
That's the best I could do.