It depends on the PYPES system. A friend installed one on his '65 and it's tucked up tight, fits perfectly, sounds great, and has no leaks. Personally, I give a big thumbs down to Flowmaster.....their systems are overly loud and tend to drone under the car. They sound wicked for the first day or two, but if you drive the car, they become obnoxious and tiresome in a hurry. Just my 2 cents.....

 

I have Pypes on my 65, Iam pleased with them, they fit very well and not too loud inside the car, but they do tend to blow the doors off of whatever is beside me

 

I like this:

Expensive, but so cool...

 

I got the summit 2.5" pipes, perfect fit for half the price, running Magna-flow mufflers and they sound good with no drone and get throaty when you get into it.

 

On my 1970 GTO with 455, etc., i went with H pipe, magnaflow mufflers and pipes out the back and then added resonators a short while later right next to the gas tank. They tucked in nice. I like the difference in sound. Not original but not like everyone else either.