sb 4 speed questions on 63 dart gt

http://www.slantsix.org/forum/viewtopic.php?t=51304&postdays=0&postorder=asc&start=60

dont really need the manifold it can be done much cheaper and easier. im running the J-pipe now and im over 300hp. not sure how much more i can get out of it but it doesnt seem to be a limiting factor just yet.