i have a pretty healty big block in my car and the way it dumps under the car is a pain in the ***. whould a maganaflow 3in cat back and i will make my y pipe (sense no one makes then for the hooker bbc headers) be enought for a healty big block

 

I personally would do 3 1/2" to 4" on a "healthy" big block. Either get a custom exhaust built using said size mandrel bent pipe or go with a Mufflex system.

 

Ya, if it is a big block I would deffinetly go with 4" or so if you are using only one outlet