Gen1 PAIR block off to Reduce Backfiring/Popping
The PAIR system sucks cool fresh air from the air box and releases it into the exhaust. The higher level of oxygen in the exhaust reacts more readily with the catalytic converters and produces cleaner emissions. When switching to slip-ons or a full system, some or all of the catalytic converters are removed and the additional air in the exhaust seems to make unburned fuel that is expelled in the exhaust ignite much easier and we get some popping on deceleration.
This is the simplest method to disable the PAIR system if you find the popping noise bothersome. It should also prove valuable if you are data logging or tuning because your o2 sensor will not give false readings based on exhaust that is mixed with fresh air from the PAIR system. There are a couple more elaborate methods (which are no more effective) that involve removing the PAIR system and blocking the passages that are left (see PAIR Removal-Block-Off Plates Install). I chose this method because I wanted to test how well it works before doing something more elaborate.
Do First:
Remove from RH side of bike: ram air tube cover, forman, tank cover, lower faring and side fairing (see Fairing Removal).
You will need:
one 5/8” diameter wooden dowel
one #8 hose clamp
sand paper, coarse and fine grit
pencil
saw
screwdriver
silicone lubricant
1. Locate the grey clear air hose which is inserted into the bottom of the air box. The hose is marked with a piece of blue tape in the photo below.
Simply pull the hose out of the grommet under the air box that the hose is inserted through. 
2. Insert 5/8” diameter wooden dowel into the hose. It will fit very tight. I thought it best to reduce the diameter of the dowel to avoid stretching the hose or distorting the rubber fitting that the hose fits into when the hose is reinserted into the air box. A tighter fit should be safer and seal better but it may also stretch, making restoring back to OEM difficult if the rubber parts no longer fit.
I sanded the dowel down so that it was closer to 9/16” and tapered a bit toward the tip so that it could be pushed into the hose (or removed) easier. I also rounded one side of the tip so that it would fit into the bend in the hose smoothly. I used a fine grit sand paper to remove any wood fibers that could come off of the dowel when installed into the hose.
When the dowel is shaped to make a good, tight fit without distorting the shape of the hose too much, draw a line around the top of the hose to mark where the dowel should be sawed off. 
3. Sand the top of the dowel with fine sandpaper to remove any wood fibers that could enter the air box. 
4. Press the dowel into the hose.
Tighten a #8 hose clamp against the clean air hose where the dowel is inserted at a point just above the bend in the hose.
If anything, the PAIR system will tend to suck the dowel down the hose so there is little danger of the dowel coming out and falling into the air box as long as the dowel fits in the hose tightly. I do not know if a strong backfire in the exhaust or detonation in the engine could cause the dowel to eject into the air box but if it could, the hose clamp is an added measure of protection.
5. Apply a film of silicone or spit (your preference) to the clean air hose and reinsert it into the grommet in the air box.
No air can enter the PAIR system. Backfire/popping should be reduced to a minimum and exhaust sampling accuracy should be improved.
* Last updated by: Rook on 9/5/2017 @ 4:05 PM *
).
