A lot of trans companies will make it shift 1-2 very hard like that for performance. It won't hurt it. Its all on the servo thats in the side of the case on the passenger side. My truck does the exact same thing that yours does. On hot days with my 102,000mile, 20 year old, worn out 305, I can get a second gear scratch on brand new Eagle GTII's...

If you don't like it, fix it. But personally I love that neck breaking jolt that you get when it hits second. And yes, the adjustment is in the TV pressure. If you turn it down, the shift will be more mild. The more you give it, the harder it hits. I have mine turned all the way open to help with milage on the highway. TV pressure in the 700r4 makes it shift later and more firm. If you like it, leave it alone because it won't hurt it. I've had my trans. in my truck for about 40,000 miles and it has had that very obnoxious 1-2 shift since day 1.

Actually MOST tranny shops replace that servo with what's called a "corvette servor" because it firms up the factory wishy washy 700r4 1-2 shift. Thats just my take on it. If your worried, you should call your builder and ask him about that monstrous 1-2 shift.