Thinking about replacing the cap with a downdraft tailpipe tip.  Only cheap one I could find that was short is seen below.  It is $20 for a pair of them(free shipping).  3.5" inlet. Mild steel.  Should fit over the Grand Slam chimney without need for screws or weld, since it is a vertical mount. Can rotate it to avoid the wind and rain (I usually roll the grill under my porch for rain anyhow) Can slip it off to put the grill cover on.  Plan to paint it black.  Anyone interested in sharing the pair?  I will keep one and ship the other (at lowest cost avail.) PS the diameter of the exhaust on the GS (and probably the GI) is 3.5" EXTERNAL so should be a nice fit.

Should look good but with it going over smoke stack, I would worry about any black moisture running back down the pipe and on the outside of your existing stack. Just a thought.

Mudflap

Should look good but with it going over smoke stack, I would worry about any black moisture running back down the pipe and on the outside of your existing stack. Just a thought.

Mudflap

I guess you mean black soot moisture?  Not sure that would happen.  In any event, I would be taking it off between cooks and storing down under (I have a large plastic tub on the under shelf when not cooking.) Also, the entry is 3.5" for about 1.5" so I could snug the exhaust tip up against the pipe to prevent leaks.  I went ahead and ordered them and will see how it works out.  Cheap enough to experiment with. If I like it, someone else may want the other one.

I’m interested. Post how it works out.

I’m interested. Post how it works out.

Will do MPO9.  I've seen similar chimney caps before in the old Pelletheads site. 

Should have it by the weekend. 

This looks like a good mod for the money. I like the idea that you can adjust the exhaust for wind direction.
I'm interested in how it actually fits and how easily it moves. My initial thought is it will be quite snug. I'd hate to see it turn into a battle for every cook.

Will have it Sat.  Will see how it fits before I paint it.   Pics to follow.

What I'm I missing? What's wrong with the cap that it comes with?

What I'm I missing? What's wrong with the cap that it comes with?

I have been wondering the same thing.

 The tailpipe will allow the smoke to be " directed ", that could be advantageous.  Rotating it on the stack could grind away at the finish resulting in rust.   

I may be outsmarting myself.  I imagine that facing the opening away from the wind will keep wind out of the chimney, but perhaps it will also cause a venturi effect and suck the heat and smoke out of the pit faster.  Of course it could do that with the original cap as well but probably to lesser extent. Cheap way to find out is to try it and see how it affects basic function.
Surprised that no one has suggested merely buying a longer bolt for the cap so as to set it higher for more air flow. (and still maintain rain blocking effect. )  We shall see. 

Surprised that no one has suggested merely buying a longer bolt for the cap so as to set it higher for more air flow. (and still maintain rain blocking effect. ) 

I think longer bolt wont work in windy conditions. Just like an umbrella you don't raise it in the wind you lower or tilt it.

Mudflap

An other option to wind blocking is to hang a charcoal chimney over the existing cap when required.

Here 'tis.  It came in a smoked coating which I could not completely wipe off (looked like soot).  Did my best and then found it fits perfectly over the chimney.  Not much wind today, but I am "burning it in" at 350*.  Have my Maverick grill temp tester installed at grate level in the center. Here are initial pics and installation:

Ran the GS at 350 for 35 minutes.  It stayed at the set number on the pit readout and the grill temp on the maverick was from 342 to 353.  Then lowered the temp to 220 and closed the upper butterfly valve on the Godke to mimic smoking at low slow.  Actual temp at the middle of grates ran between 219 and 225 so that was wonderful as well.
Please Note: I have previously accurized my PID set/actual temps on another thread and essentially the downdraft and exhaust tip have not altered the results to any degree.  It was nice to direct the smoke away from the work area when I was in and out of the pit.  Also, tonight I made burgers on GrillGrates at 450* with no observable changes noted.
I like the exhaust tip and have one extra for sale at cost plus cheapest shipping--should be around $15 total. You can private email me for the particulars.