Maybe put this into the wanted section, that's what I did. Definately has a better pull with that pipe connected. Does sound nice without it tho doesn't it? 
Mine definately had better pick up when I connected it. Not drawing in all that hot air from the rad. Smoother pick up rather than much more speed etc.I wouldnt bother connecting the resinator box back up.
As said it wont cause any idling issues out and it zaps a little power aswell.
If you have the pipe connected so it doesnt draw air by the rad and dont connect the box!
Been done on the RR years ago and the 180s tested with the boxs off made a couple of horses more iirc. Not that it would be noticable on the road though.
Have you got any pics of the kit, I found the one on my vectra gsi to be quite good! You looking to get rid are ya?? Did it sound throaty as my old one just sounded normal.I've got an unused Pipercross Viper Kit. I'd had it a few months then decided I'd better fit it. What a pile of junk. Badly made, dreadful instructions, and I had no idea just how the top bracket was supposed to fit. Also, it sits far too close to the rad, a slight engine rock or loose jubilee clip and the whole thing looked like it would come off and wreck the rad. Waste of £200.