That its not really power dependent. The two top guys in my city are a new ZO6 with full slicks, and 88 crx with less than 90 wheel hp, but a killer suspension and driver.
Some advice is just run on your wastegates for the first run than start ramping it up after each run. My dumbass ran on 16lbs and it wasn't as fun or as quick as 9 lbs of boost. I dropped a little over a second on my lap.