Welding torque boxes...tips?

I would not just weld the seams. The torque boxes are about as thick as a frickin soda can! I would recommend buying the torque box reinforcement brackets that some of the speed shops (on or off-line) sell. Or you can do what I did and just cut, bend & fabricate your own brackets. It's really not that hard as long as you have a band saw(or a hack saw if you're feeling buffed) , a vice & a hammer. I reinforced mine with 4 brackets on each side. You DEFINITELY need to remove your back seat though...unless you want to catch your car on fire. Believe me, the metal is so thin where you have to weld that there will be sparks & glowing orange metal underneath your back seat. So do yourself a favor and remove it and have a water soaked towel right near you while welding incase of a little spark up. The insulation &/or carpet can easily catch fire. You should be inside the car with the wet towel & the back seat out (just the bottom part) while the guy is welding underneath to assure that everything is ok. I even had to do some welding from inside the car like 88workcar mentioned. And no you don't have to remove your lower control arms. Good luck.