What kind of times/improvement

Hello my people. I just got back from the store. Ran up and got some Nitto 275 40 555R's and was wondering, given the mods and time in my sig, what kind of improvement I should see at the track. The 13.5 was run pretty much off idle and even with a little bog..and w/o the DS and Subs....please chime in...also have we come to any kind of consensus on the best RPM's etc to launch at?? 3500 and a little slippage?