460 project

just installed my 460, in my 64 fastback, got her timed and running . taking her to the muffler shop what size pipes would i need . only damage i did was sratch the fender when i took the front bumper off. all the way to the metal, 1inch and a half long[img]/phpBB/images/smiles/icon_cry.gif[/img][img]/phpBB/images/smiles/icon_cry.gif[/img]. well yall have a good day

For that size motor, you need at least 2.25 (2 1/4in) pipes. Anything smaller and you'll choke of some of the top end power.

I would suggest 2.5 (2 1/2 in), if your local shop can "do" mandrel bends or you can find either a pre-made kit or the correct pieces to take it over the rear axel.

Three inch exhausts are the hot ticket today, but they present a lot of fitment problems...mainly trying to hide what amounts to sewer pipes,behind the frame rails. Unless you are making 500 hp or better; I'm thinking 2 1/2 is a better deal, much cheaper to have installed, easier to "tuck" up under the body and generally quieter...easier for you and your neighbors to live with [img]/phpBB/images/smiles/icon_smile.gif[/img] ; life is easier that way. I doubt if you'll find 3in mufflers in most shops anyway. They'er something you usually have to pre-order, as well as find a shop that really knows how to install them right, otherwise they will be butcher...making your car look like a demo derby candidate.
In my mind, you need to plan the exhaust system with as much care as you spend picking a cam shaft. It has a lot of influence not only on how your ride will sound, but also has influence on where the power comes on. Never discount the effects of back pressure. A little is good, too much will choke your engine.

yeah im going to go with 2 1/2 s its all stock any way[img]/phpBB/images/smiles/icon_bow.gif[/img]

You probably thought about this already, but just in case you didn't think about it...have them join the dual pipes with a same diameter cross-over, about 30 inches back from the where the head pipes level out under the floorboards, somewhere before the mufflers.

A few inches behind the transmission cross member should be about right. It will make the exhaust mellower and increase torque, power at lower rpm.