Hey richard....your nozzle is way to far away from the elbow ....just like wickedtalon talon mentioned.

There is way to much intake tube there for the nozzle to work right or as it should, you are losing so much potential.

That and running the risk of leaning out, as the fuel is heavier it has the chance of dampening the intake tube rather then staying atomized with the n2o and going right to the intake mani itself. It will also soak that elbow as it tries to round the corner which may of been a direct result of your intake backfire. The reason I say that is...it may not of happened before..but as carbon dirt ect builds up in the cai...it gives something for the fuel to cling to.

It should be no more then 6 inches away from the TB to get maximum pontial and that is for a wet kit only.

And though the odds are slim...you have that nice little vent tube
to the valve cover that you run the risk of n20/raw fuel getting in.

Use this to help with your jet sizes....one of the easiest calculators out there for getting the shot combo you want.
http://www.robietherobot.com/NitrousJetCalculator.htm
I have ran just about every n2o kit out there. :P