Yeah.. The 1 inch t-bars have been in place since 2003. During the most recent motor install, the only suspension/steering part removed twas the center link... Sorry, I forgot to mention that part. No need to fully remove it either. I just remove the nuts at the idler and pitman and pull the CL down. This is necessary to slip the headers in place.
If you dont intend to keep or sell the old T-bars, you could cut them out with a grinding disc if you want. Most headers are designed to fit around the t-bars anyway. Keep in mind though, that when the header companies design their products, they are most likely making patterns based on an unwrecked or twisted chassis and with factory motor mounts in good condition. This means that if your car has some battle scars, you may need to dimple a few things to get the pipes to fit and NOT rattle.