Just like to add a few details to help others who may be keen:
1. I confirm that my (frankly embarrassing) popping on decel with the 4-4 system has now almost gone.
2. You will need 2 x 13mm (half inch) blanking caps (also known as radiator caps). This is the entire cost of the job
3. There are 3 hoses as noted above. All of them pull off by hand and a pair of pliers is helpful.
4. The front 2 hoses attach to the pair valve and engine.
5. The third longer hose attaches to the airbox. You will need to take off the right hand side panel, remove airbox cover, remove airfilter and stick your hand in the hole. Just up on the right you'll feel the round hole which connects to the hose. I blanked this off with some rubber and high-temp silicon. I suppose tape or a rubber plug would be just as good.
6. I didn't remove the tank however, I did raise it at the front and insert a rolled up towel to keep it in position. I used a small strap over the tank to secure it "just in case".
7. I also removed the valve and simply cable-tied the connector up under the tank with a bit of electrical tape over the end of it.
Beers !