Hey whats up guys

So I just got done installing the D/P, and let me tell ya, it wasn't what I thought it was going to be.

The bolts right behind the u-bend came off somewhat easily, and one of the bolts behind the exhaust manifold came off suprisingly easily, and the other, half-way into, snapped clean off. The bolt was still in the flange and out the other side. So I tried to drill it out. That took all of about an hour to do. Once I got the bolt drilled out I decided to just use a good old nut and bolt, which tightening wasn't a walk in the park.

So I got the o2 sensor back in and tightened, all of the bolts good and tight, and I was all set. I decided to take it on a little spin to see how it felt. First off it sounds really cool now, it made a significant difference in the sound. So the ride went good and I'm on my way home and I give it one more WOT run and I hear a very loud leak. My brother was in the car and he heard it too. So we got back, the gasket on the back of the exhaust manifold was smoking, and we determined that thats where it came from.

These ARE new gaskets that I ordered with the D/P so I guess I didn't tighten them all the way? Could it be something else? I was too frustrated to work on it any more, plus I would have to let everything cool off again. I just don't know what to do guys. Hit me with any imput you might have.