i am starting on the exhuast on my trans am. I want to use shorties and wanted to know if the stock y-pipe would bolt up to the flanges or not?Its an L69 by the way if that helps.

 

There are no headers that will bolt up to the stock exhaust system. Thats why most shorty header sets have an optional Y-pipe of their own.

But you don't want to bolt it to the factory exhaust anyway. The L69 system is probably the best system GM put on a 3rdgen, but that doesn't make it a good system.

My advise - find some shorty headers you like, look at Hookers or Hedmans, SLP, etc... and buy them, and buy the Y-pipe that goes with them. Not all headers will have a Y-pipe, but most of the better sets do.