The other day while driving, my 1996 Maxima GLE got loud instantly. I had already replaced the muffler last week. Looking under the car, I found the flex pipe (?) disconnected from the cat. I found a replacement y pipe, but I don't know how far it goes. Does this new pipe go all the way to the cat, or do I need a pipe to connect them? Will the Ebay pipe without the pre-cats add a noticeable amount of power, and will it be louder? Should I go with the factory-style pre-cat y-pipe from Rock auto for about the same price?

http://www.ebay.com/itm/1995-1996-97-1998-99-Nissan-Maxima-EXHAUST-FLEX-Y-PIPE-/200451555229?pt=Motors_Car_Truck_Parts_Accessories&hash=item2eabd7ff9d&vxp=mtr

 

It should go to the cat.
Power gains might be 10-15hp
Louder, not really with a stock muffler

Last question is really up to you...

 

Pretty sure that can be welded if you are strapped for cash. You must reside in a snow region with all that corrosion you have on the undercarriage.