340 headers?

I disagree, I think 50+ HP is a bit of a stretch. My car is a 14.2 sec car with street tires. Thats barely 300 horses maybe a little more. The elevation is somewhat higher here plus the air is not that great for big HP. I noticed a bit of a difference a long time ago when I put the headers on but not 50 HP worth. I have the manifolds and bolts and all in my garage, I don't have anything but flattened out headers on the Dart right now, so the manifolds are going on, I will G-tech it before and after and we will see. Like I said before, the NOS will more than make up the difference. Have you ever run NOS on your car? If you have, then you know what I mean.