Installation notes:
You have to play around with their exhaust flange, see how it best fits your head. It can go on 4 different ways, but on mine it only fit right 1 way, and I had to trim one small fin about 1/16" to get it right. They give you two gaskets, stack them to get a proper fit/seal, that's the way mine was done from Enfield.
The pipe is bigger externally, once installed my rear brake lever hit on the bottom of it. My stop bolt for the lever was already adjusted all the way down, so I had to take the jam nut from the top and put it on the bottom. Once I did this I made a minor adjustment to keep the lever off the pipe.
The o2 sensors in a slightly different spot, so I removed the zip tie for a little more play. I put the zip tie back on to keep the horn and clutch cable in place. Wind the o2 sensor up a bit counter-clockwise, so when you tighten it down the wirings relatively straight.
The muffler/bracket/clamp all went together without an issue, simple and well thought out. My muffler didn't have an insert, the hole is there for a bolt, but nothing's there to remove. I'll have to check their catalog, but I think it says something about that. I took a pic looking up through it, it's like an old glass pack, straight shot pretty much. I rode it into work tonight, sounds great, no backfire at all.
Last but not least, the tappet cover. 2 of the 4 allen bolts where stripped from Enfield, but I got them out by tapping torx bits into them. It looked like the engine builder liked his silicone sealer, he must have used damn near a tube of it. I cleaned it all up, went to the local hardware store for new 5mm bolts (they had them in stainless with phillips heads, that'll work for now), and put it back together. Love the look of the lettering, no more "EFI", lol.
I'd like to take a second to say, these parts are all top notch. There's a premium to pay for them, but the chrome looks good, the welds are great, and everything fit the way it was supposed to. I'd recommend these parts to anyone that asked.
Now, if only I had that case gasket.....