It should help reduce the heat issue with 1-5 dumping into to 6 before exiting, though I don't think you will get much in the way of performance gains, then again it didn't cost you $700 either <img src="/forums/images/graemlins/smile.gif" alt="" />

As mentioned on yotatech, you will want to reinforce the "Y". I would weld some 2" bands across the "Y" on each side, and then maybe weld in a piece of tube between the two down pipes.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed