I've been bouncing around between little tasks as I wait for additional stuff to arrive (like more electrical stuff to finish up the FWF wiring). That makes it a little tough to document in a way that would make any sense to someone not seeing the big picture, but I'll give it a shot.
One of the weaknesses I've read about is the cabin heat. Apparently a lot of people find that they just can't get enough warm air from a single muff setup like I have. My Vetterman exhaust has one heat muff - basically an 8 or 9"ish cylinder that goes over part of the tail pipe and has an inlet and exit. The inlet gets fresh air from the front of the engine just as it comes into the air inlets behind the prop, and the exit takes the heated air from the muff and sends it via scat tubing to the cabin heat valve. In order to get more hot air, I basically need to increase the surface area of hot metal. After seeing some different ideas on VAF, I figured the best approach was to bolt metal heat sinks around the tailpipe so the incoming air had more hot metal to move around. I took some measurements and made a design in CAD and sent it off to sendcutsend.com to have it cut out of 1/16" stainless. It's pretty amazing that I can design something at home and a week later have custom parts in hand for $30. My design essentially has a strap that will bolt around the tailpipe and tabs that I will bend 90 degrees up into the airflow.
The gotcha with this design is that the heat muff isn't centered on the tailpipe - it sets very close on one side and has about a half inch of space on the opposite site (to make a better path for the air). To account for that, I designed my parts so that the tabs are smaller on one side. Here's what the raw parts look like:
My first attempt showed me the error in my design - when I did the math to figure out the length of the part, I neglected to take into account the 1/16" thickness. That means the overall length is a little short and the tabs stick up a little further than I anticipated. It's all fixable though. I'll just bend the tabs for the bolts a little closer to the bolt holes and I'll start the bend for the tabs so that they are a tiny bit shorter. Bending the tabs is rough on hands, so I only did a couple of rings today. I'll just do a few here or there each day until I finish up.
I also received my alternator this week. Van's sells a Plane Power alternator with their kits, but they are known for having terrible reliability. B&C alternators have a stellar reputation, so that's what I went with. I went with a very different style of alternator than is typical though. The most common B&C alternators use a remote box for the electrical brains. That's fine, but requires you to run quite a few more wires from the engine back to the boxes aft of the firewall, especially if you have a backup alternator as well. Last year, B&C came out with a new style of alternator though - one that has all of the electrical brains in the alternator itself, including overvoltage protection. So in essence, it mimics an automotive alternator with the addition of the overvoltage protection. There are some cons to these units vs the old style, but for what I need, the pros far outweigh the cons (including the fact that they're about 1/2 the cost!). If it were any other company, I probably wouldn't roll the dice on an unproven alternator, but B&C is as good of a company as you can find, so I'm fine being an early adopter of their new units. They are getting ready to release the spline drive alternator for this line as well, so that's what I'll use once I decide I'm ready for a backup alternator.
