I'll add a plus one for the Turbo Heat Muff. But let me back the bus up just a bit.
I originally had the dual pipe heat muff that attached to the straight sections of #1 & #3 at the bottom of the cowling. It provided acceptable heat when needed, but it wasn't going to roast your feet. However, over time I hypothesized that it was blocking some of the engine cooling exit air, or at least creating turbulence of the outgoing air from the cowling. I removed the dual muff for the summer months and found the CHTs came down more quickly after power reductions, and CHTs were lower in general. With the summer we had this year, that's saying something. Now, some may chime in and say I'm full of crud, but that's my experience. Did I run hours of emperical tests with lots of documented data...no. Just flew it for the summer and observed what I saw.
So when it started to turn cool this November (it's Texas), I installed the single-pipe Turbo Muff up higher on the #1 exhaust. Plenty of heat--at least for our climate--with the provided restrictor plate installed. CHTs still very good, and even better with the cooler weather. And the installation is much easier than the dual-pipe muff.