High revs before shifting, need a tuner?

We have a 2004 GT 4.6 2V. Just did a tubular K-member, camber plates, a-arms, and bumpsteer kit to make room for the turbo kit we are going to install. Ever since we bought this car since this last winter, it seems to rev higher than normal before shifting. My brother has the exact same motor in his Mercury Grand Marquis and it shift completely differently, which really changes the way the entire car reacts. I'm fairly sure that the person who had the vehicle before us tinkered with it as it came with straight pipes, Air Raid CAI, and the engine bay was spotless. We put on some Flow Masters, but it's still relatively loud, especially since it has to rev high and seemingly stay there for a bit until it shifts.

Is our only option to get it to a tuner to modify these shift points or is there something we can do to maybe ensure we can get this back to stock?

Thanks!