Hey guys....I bought my car with N20....only had 5 bottles ran through it, but does nitrous make your car run rich? ive owned it for about 2 weeks now, and i havent sprayed it yet (gotta get a refill) i smoke only when i stop and rev it, dosent do it at idle, and 2 mechanics think im just running a tad rich....Also i have a bad Cat on bank 2....so here are some questions.....will the bad cat make me run rich? are you suppose to run rich b4 you spray?

 

Properly setup no, you should be capable of running a 13.1:1 AFR NA, and then on the juice hit your target AFR, depending on power level is how I set mine up...for me its in the 10's but progressively drops down as the nitrous flows more.
I would fix the cat issue b4 spraying, a clogged cat will nuke your setup with or w/o juice. What color smoke? Black is rich, grey is oil, white is coolan for the most part. If your gray smoking at stops, it sounds like valve seals/valve guides and oil with compression and nitrous is not healthy, tends to induce KR.