Ok, ever since getting my SFCs done I've gotten this loud bang whenever I hit a bump from underneath the passenger's side of the car. A friend sitting in the seat says it feels more like directly underneath him than from the direction of the tranny.

The SFCs are the Alston bolt in type and they are both bolted and welded in.

Its not the tranny mount as its brand new and still in perfect shape.

Its not the cat- if I put the car on ramps and try to shake the cat with both hands the exhaust barely moves.

It happens on pretty much any bump except for the smallest ones. Any suggestions?

 

check the welds on your sfc's are still good and take out the bolts in your sfc's if you've welded it in.

 

Check your upper shock mount on that side. It's right behind the rear seat, under the carpet, behind a big block of foam. It just goes into the car's sheet metal, and the stress of absorbing shocks will eventually punch right through the floor pan. If it's fornicated, the other side probably isn't far behind.

I doubt it has anything to do with the SFCs, unless either their weld broke, or something else is loose and bangs into them such as exhaust.