[rpreston]

I'm not looking to get bigger than stock. I just need to know whether the Y pipe thru to the back of the Cat were the same diameter on a 1990 with a 350 as compared to a 1990 with a 305. My truck still has the original exhaust that came with a 305 but I now have a 350 in it. If I buy a set of Gibson or Flowmaster's for a 1990 with a 350 engine, will they match up to my existing 305 stock Y pipe/Cat? If your 1991 350 had 3" pipe from the header outlet thru to the muffler then they are diffinitely larger then my current stock 305 exhaust. If that's the case then I need a new Y pipe and Cat also. (or a straight pipe to replace the Cat)