63 Tempest 4 cyl engine
 

I recently purchased a '63 Tempest with a 4cyl engine. I've heard that you can increase horsepower a bit by splitting the exhaust and installing duel exhaust....anyone try this ? and is it successful ?

That is one way to do it if you have a hedder made for the 4 cylinder. But, it should be equal length tubes. Pair the # 1 & 4 cylinders together & # 2 & 3 together. A much cheaper way is to get a used 3 tube hedder. You should have at least a 2 1/4" pipe all the way out the back. Find one that looks like the picture, right side 3 tube hedder. You will have to fabricate a block off plate for the bottom of the intake manifold where the exhaust crossover pipe is bolted.

You may want to retain the stock exhaust manifold. If you do, have a system installed from the manifold back, with a 2 1/4" pipe.

Thanks for the info !!

I did a quickie ovehaul of my 4 banger 63 and in the process added a 3 tube header left over from my 67 GTO. Also had some exhaust pipes laying around so ran a single 2.5 pipe and turbo muffler to the back bumper. Everything fit well and it ran fine. Gas milage got worse though.