360 header gains?

My educated opinion only:
The expense of replacing your hookers with tti will not be justified. Maybe ten hp, so $100 each
The expense of an x-pipe will not be worthwhile. An H-pipe will accomplish 90% of any gain you would get from an x, be much cheaper and easier. You can keep the exhaust you have.
Engine masters did a test of crush bent pipes compared to same shape mandrel bent. They found zero hp loss from crush bent pipes.