3 inch exhaust with manifolds??

I have a 68 coronet and since its a bigger car than a dart I was thinking of using a 3 inch exhaust kit instead of the 2.5"

is this a good idea with stock HP manifolds?

Its a 440 HP from 67 with 915 heads and the goodies but to stock 67 GTX specs. Nothing wild, just a badass street car is the goal.

Someone told me the sound is different between 2.5 and 3 inch exhaust. ......???

The 3 inch costs a bit more so I am wondering if its worth it or just a waste of $$ considering the other factors of the driveline combo and intended use.