If my SF were welded in without load on the suspension, how bad would that be? Should they be unwelded and then rewelded?

 

I'm sure people will come in and tell you it will be bad. You want the car to be strengthened when it is in the same state in which you drive the car. I asked this question a while back and also got the response that as long as the frame rails are level with either other, it shouldn't really be a problem. (note: my car is just a shell)

So, will it make a difference? Yes.
How big of a difference? Dunno.
Would it be something anyone would ever be able to notice? Probably not.

 

Basically you just don't want the chassis to be jacked up where it has and arch from a jackstandon the subframe near the trans. What that does is unloads the frame where the front and rear of the chassis are dropped and the middle section is raised in a very slight banana shape arch. By the car resting on the wheels it loads the chassis to sit with the center of the car non arched upward. and the SFC's are welded into it in the natural chassis state.
Long and shot of it is as long as your doors close and line up properly you are fine.

 

i just had my SFC welded on, and its much easier with a drive on lift, unfortunately my guy had a frame lift and it had to be adjusted to ride height...