Very cool project. I'm very familiar with the VW's. The distance from your headers to the back of the vehicle is much shorter than that of many cars. Therefore, your exhaust will be louder unless you go with either a 2.25" or 2" pipe. You can also use the 2.5" and purchase some milder mufflers. Magnaflow makes a set which would sound pretty good. Sometimes a muffler shop will put various muffler on so you can hear the sound and loudness. Being that your putting the SBC in a VW, I would personally like to have people know there is a V8 sitting under the hood. I'm not an exhaust expert, but I would think 2.5" pipe to a mellow muffler going to your rear axle would be a nice, clean setup. If it's too loud for your taste, run 2.25" or 2" piping out to the rear bumper and put a couple of chrome tips on it. I'd love to see that project when the engine is in... Very cool...
