An exhaust system is a means to an end in most cases. Your hot rod has to have one to run legally on the street, and most of the time you want it hidden as much as possible up under the car. The exhaust on my '32 roadster has served its purpose for 30 years and was starting to show signs that it had had enough. The hangers had come loose, the tailpipes were rattling against the frame, and the old glasspacks were due to be replaced.
Most pieces on the car are pre-1960, so I wanted to continue that theme when it came time to replace the exhaust. My plan called for replacing the old Hedman (I think) headers that had a strange flange where it met the head pipe that featured two ports and three bolts. New gaskets weren't available and every attempt I made to seal it generally only lasted a few hundred miles. The last attempt was cutting a copper gasket, which worked the best but was a day late and a dollar short, as I had already determined that I was going to install a set of GM Ram Horn manifolds.
The muffler choice needed to keep the retro feel as well, so I looked into the Smithy's mufflers and found just what I needed. They looked the part, but you never really know what any mufflers are going to sound like with your particular engine until you get them installed. It was a chance I was willing to take to keep the look I was after.
The engine in my roadster at the moment is a 327ci small-block Chevy that was dyno'd at 345 hp (much more than the '39 Ford box can take). Future plans call for the 283 I pulled out of it to get a mild rebuild and reinstalled. Taking this into account, I opted for a dual 2 1/2-inch exhaust up to the mufflers, which are 2-inch, maintaining that size out the back. I didn't care if the engine got choked off a little; in fact, that might even help.
Once the system was installed, I couldn't believe how good it sounded through the mufflers. It has a nice mild tone at idle, similar to a Flathead, which fits the style of the car quite well. A flick of the switch then opens the cutouts and it's a whole different ballgame. Suddenly it sounds like a wicked small-block with some cam. I can honestly say that the cutouts are some of the most fun I've had with a car in a long time.
I know this has all sounded too good, so I have to admit there has been a downside to this install. I like the sound of the exhaust both through the Smithy's mufflers and open through the cutouts so much that my mileage has dropped off quite a bit because I've been burping the throttle too much just so I can hear it. If that's the price to pay, I guess I can live with it.
I figured that as long as I was going to be replacing the entire exhaust system I might as well have some fun once it was done, so I picked up a pair of 2 1/2-inch electronic exhaust cutouts from Doug's Headers (also available for 3- and 3 1/2-inch tubing). They're made out of stainless steel and work with a rack-and-pinion drive mechanism. | 
Doug's Headers was good enough to offer up the services of Kenny and Chad at their R&D facility. Once I had the roadster there, Kenny and Chad grabbed an assortment of pre-bent tubing (available through their catalog) and started figuring just how the pipes would snake their way through the undercarriage. | 
After the new head pipes had been welded up, it was time to install the exhaust cutouts. The cutouts require a short Y-pipe to branch off the exhaust. Chad cut a few pieces off a U-bend pipe and welded them together to get the curves he wanted. He then held it to the head pipe to mark where to cut the hole. |
It was then opened up using a cutting torch and smoothed with an abrasive wheel. The Y-pipe was then welded on using a MIG welder. | 
A flange needed to be welded to the end of the Y-pipe so the cutouts could be bolted on. This needs to be done after the placement of the cutouts has been determined because the flange on the cutout comes welded so it can't be rotated to make it level. Once the head pipe was loosely bolted on, the cutouts were held in place with another flange bolted on to determine the clocking of the new flange. Once the position was marked, the flange was welded to the Y-pipe. You can also see the short dump tube that has been welded to the cutout here. | 
When finding a spot for the cutouts, make sure there's enough room for the door mechanisms (arrow) to extend (about an inch) when opened. |