@marcfoster1 - Glad that you found a way forward. I’ve always felt that connecting an exhaust system directly to the exhaust port on the Bullet could be problematic. I’ve owned several electric drum roasters that had batch sizes large enough to produce enough smoke and odor that it needed to be managed outdoors. On all of them, I used an active (but detached) exhaust system. That means I have a variable speed fan that can push the smoke and odor outdoors, but is not directly connected (contacting) the roaster. I have a setup like that on my Bullet and it has not caused any roasting problems or errors.
I believe that Aillio’s thought with the whole 3D printed adapter was to provide a direct-connect, passive exhaust. But that can invite several problems for the roaster and/or the exhaust line (especially for longer runs). In addition to smoke and odor, the exhaust from drum roasters carries roast dust and moisture. That moisture can collect in the exhaust line if it is not being actively removed.
A direct-connect, long exhaust run (with no active fan to help promote flow for the line) is not helping the roaster or the exhaust line’s function. The Bullet’s exhaust fan isn’t really powerful enough to manage that situation. Even if you look at other professional grade roasters of 1Kg and larger, they incorporate a separate active exhaust design. For anyone that is concerned about an active exhaust system’s impact upon the roaster’s heat performance, installing a Magnehelic (that samples the pressure in the Bullet’s drum exhaust) can tell you if there is a problem (or not). 
Glad you are roasting again and I’d suggest modifying your exhaust setup to include a non-connected, active, variable speed fan to manage the smoke, moisture and odor for this particular roaster.
I have a lightweight box that I built that sits just around the rear-end of the Bullet as a pre-collection chamber. The box is positioned just behind the Bullet’s side perforated vents so that it doesn’t block or impair that flow. It has an integrated hood at the top of the chamber that sits a few inches above the Bullet’s open exhaust and then connects to my 4" exhaust line. Half-way down the exhaust line, I have a variable speed fan that has a good range of low speeds to push the exhaust outdoors. There are lots of different ways to do this, but the main concept is not to have the exhaust system connected direct to the Bullet’s exhaust.
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I’ve been doing a lot of roasting on my V1 (recently upgraded to the new IBTS) for the past 2.5 years (over 2000 lbs roasted). I’ve found the sweet spot for me is 900g batches. I’ve also been using a 6’ exhaust venting out my window in the basement with an inline fan to help carry out the exhaust. The inline fan is placed far enough away from the exhaust so it doesn’t affect airflow but enough to help pull the exhaust through the vent and outside. True, you do have to keep the exhaust vent clean as it does build up with oils and dust…but a thorough clean every 6 months has worked well for me!
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When I picked up my Bullet from Sweet Maria’s, Thompson Owen was around and we chatted about the roaster for a bit. He recommended just using a vent pipe above the exhaust port without using an adapter and that’s what I ended up doing, hooking up a vent pipe into my exhaust fan in the range hood I have hung in my roaster bench.
It works well and I don’t notice excessive smoke leakage.
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I should note that in the Aillio Bullet manual, they do have a section titled “Venting”. It mentions using venting within a maximum run-length of (3M or ~10 feet), etc. That statement would indicate a passive vent and probably assumes direct connection to the Bullet’s exhaust vent. That section also says that if the vent exceeds a 3M distance, a suction fan is recommended (at the end of the vent line), but can affect heating performance.
My total exhaust run is 10feet and I have a variable speed fan mid-way in that setup. The important difference (as several here have noted) is not being direct-connected to the Bullet’s exhaust.
An update regarding the use of the inline fan and the IBTS. Prior to installing to the new IBTS, running the inline fan had no effect on temperatures. Since upgrading to the new IBTS, I’ve noticed the BT getting as high as 200C on a 300C preheat while running the inline fan, which is not normal. Not running the inline fan during preheat allows a BT of 170C on a 300C preheat which is normal. I’ve concluded that running the inline fan with the new IBTS affects the preheat temperatures and therefore, I now only run the inline fan AFTER I charge the beans.
Thought I’d share this in case anyone else is experiencing this.
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Interesting about BT. I preheat DT to 300. And my BT always gets between 200 and 220 even. I have no inline fan. Just a 3 ft vent out the window
On my Bullet (whether reading from RoasTime or Artisan), the delta between Drum and Bean temp (before Charge) is ~130F. That difference is the same whether I’m Preheating to 437F or 480F which are the two that I typically use.
I have a Magnehelic installed on the exhaust chute (where the Bean Charge Funnel fits). With my variable inline fan set on speed 2 (out of 5), the needle on the Magnehelic doesn’t even flicker. So, no measurable air is being drawn through from the inline fan in the venting and my vent doesn’t direct connect to the Bullet.