I have an 85 TransAm factory 305 TPI. I converted it to a 350 with a carberator. I have a Dynomax Cat Back system. What header would fit the stock Y- Pipe, without modifying anything??? I also took the smog stuff off. It is a single Cat. Thanks.

 

None and it's a good thing. Using the stock y pipe would defeat the purpose of headers in the first place. It's way too restrictive.

 

Try going with Hedmann shorty headers(68470) or Hooker 2055's. They include the Ypipe for the headers to connect to.....DONT use the stock Ypipe...As said above, it would defeat the purpose of using headers in the first place. Good luck.....