First off. I got to say you do one wail of a job freshening up something. .02 tenths, that thing must have been in bad shape. The Mph didn't go up but 3 MPH though. If nothing else in the engine was changed, It sounds like your running it out the big end way on the high side of th power curve or it has a wing with the frontal area of a mainsail on the Yankee Clipper.
Al though there is no positive way to solve your problem over the internet, there are a couple areas you may want to look at. First you have gained HP and it seems mostly on the lower end of your curve. Second you have changed your center of gravity point. Not sure where it went but 10 lbs could move it considerable depending where the 10 lbs went and where the center of gravity was, and the total weight of the car. Third is, is your tire pressure matched to your new power levels and change in center of gravity? Best way to check tire pressures is with a pyrometer, even across the tire and even side to side. Well as close as you can get.
The thing to remember is your chassis and tire pressures are you springs and shocks you ran for twelve years. This isn't bad, it's just different in the same kinda way.