I understand that the chances of emitting a small flame (backfire, afterfire?) from the exhaust is greater if you are catless (uppipe + TBE) and running lean (due to aftermarket bov). I have heard that this typically happens when you are shifting between your lower gears (1st, 2nd or 3rd gear) or if you are downshift. My question is does this only happen when you are driving more aggressively (ie hard acceleration and higher RPMs) or does it happen all the time no matter how you are driving? I ask because I am planning on getting the Cobb stage 2 catless + Helix uppipe + stock BOV and I drive a lot at night and the police in my area have nothing better to do and I want to avoid giving them a reason to pull me over and I am sure that seeing a small flame from my exhaust would catch their attention. I did several searches on WRXforum.com, ClubWRX.net and here but I can't find an answer to my question. Any info would greatly be appreciated.

 

You will probably back fire but a tune helps a lot. Of throttle, in gear driving (tranny braking) is what causes it most for me.

 

Ive seen people drive next to me, not driving aggresivly at all and backfire with a little flame. I think it would happen a lot more if your driving the car hard but ive def seen it happen from driving normally.

 

Catless setup = backfire. Can't say I ever seen afterfire though from a catless setup, even though I'm sure it's possible. To me personally, it happens most when I downshift so I just avoid downshifting when theres a cop around.

 

I dont think it'll back fire if you are using the stock BOV. The TBE makes the engine run richer (not leaner). When people put on an aftermarket BOV that is not recirculating, it makes the engine run even richer at the moment it goes off. Thats the extent of my knowledge however. Anyone with more knowledge is welcome to correct me though.