i ran the gs club 2.5 inch collector on my 65-tan car like i said in my first post, before that i put the ta 3 inch collector headers on my yellow car both sat the same. years before i raised the headers on the yellow car because they were bottoming out on a stock height car never hit again.and did the same on the tan car. yes with the car on the ground and a jack with a piece of wood under the middle of the collector i would raise the car just about off the wheels on that side and then did the other side. i gained about an 1/2 inch to just almost an inch of extra clearance, one side was lower than the other side i think the drivers side. you guys can laugh if you want. if your car has been lowered your out of luck it will not make up for it.
A word to the wise here. I too have bent Headers to gain more clearance from one thing or another, and to avoid having to get my welder out again I have found ( slap the forehead moment) it’s best to bend them when they are very very hot!