I could totally see the HP going up after break in period, just because everything is BROKEN IN, everything runs more smooth... And you got your first oil change out of the way, that first oil filter probably was clogged with a lot of crap...

Then again, it could be 10000000 other factors, did you use the same oil as was in the car? Is it colder now? Is your gas better? Is there LESS oil in the engine now (less oil, less resistance)? Are you just more comfortable with beating on your car?

Actually before my first oil change, the oil level was right in the middle but after the oil change it is on the H mark so it's not less oil...actually I was a little worried that I had poured too much (5.28 qts instead of 5.125 as per manual).

After having 5 VQ powered cars they do/are known to get quit a bit quicker as the miles pile on, they tend to keep their power well into the 100's K mileage. My old 99 Max Se Limited pulled hard still till the day I sold it with 178k on it.