I am looking at the magnaflow stainless exhaust kit for my 66 coupe. They have a 2.5" and a 3". My car has a 289 with a cam, edelbrock performer rpm heads, performer rpm intake, and hooker long tube headers. I also have maier racing subframe connectors with an x brace. I am leaning towards the 2.5", but figured I would get your opinions

What do you think?

 

Go with the 2.5" setup. The 3"pipes are more appropriate for a big-block engine. The 2.5"pipes will give plenty of flow with a small-block, while providing just enough residual backpressure for low-end torque. In fact, I've got 2.25" exhaust on mine, and that works just fine.

 

You don't need 3" until you're pushing 500+hp.

 

You don't need 2.5 for a 289 with a cam either

 

Hah, true.

 

...not to mention 3" pipes create havoc in a number areas.