How do i go faster in my cobalt ls manual?

ok i've been driving it for almost a month now and am pretty good..the other day i went out and my friend timed a 0-60mph...i got a 11.46...at the time i didn't know how good that was till we got back to his house and i looked up that cobalt ls's can do that in around 8.5 seconds...i'm not sure what i'm doing wrong i start off nice with just a bit of spin on the tires..i'm guessing it's something with using the clutch to keep the rpm up high but i don't really know how to do it..i mean say im going 30mph in second gear and am about to red line at the redline i shift to third...but then i'm back down to 3 and a half or 4 thousand rpm...which doesn't give me much hp gain...what is the magic rpm for the cobalt and how do i maintain that while shifting through the gears?