Bryan, i recognise the name "dangerous" from the nitrous forum mate, small world!!
Do you get a slight "hiccup" as you back off the gas on that setup?
Or are you running a pretty small percentage increase anyway?
Cause if you are on a big shot (ie over 50% power) i wouldnt be surprised to see a bit of an excessively rich situation briefly due to the pipe lengths, they could do with being a touch shorter if its possible ideally. (not always that simple though i know!)