What is the correct design for the exhaust system on a 67 SS camaro, 396? The first one came and the exhaust ends at the rear quarter were round instesd of oval. Also I noticied the head pipes from manifolds are appox 2 1/4" and before the bend there is a weld changing down to a 2". Is this correct. Who has the Correct exhaust for this car. Thanks in advance.