Not worth it. Not good drag tires in 17's, let alone 20's. The extra weight of the 20's will kill you. They're good for the street. But if you want something for the track, get a couple of 17x9's and some M&H Racemasters or M/T ET Streets.
What gears do you have? I don't see it listed in your sig. That tire is nearly 1.5" taller than stock which is going to reduce your rear gearing. I agree with Dark as far as being a good street tire so you can run your good wheels, but the 17s would make ideal track tires.
If these would last, I'd get the 305/45-18 for the street which are .5" taller than I have now