hi all, i have a '99 uk wrx, just fitted a bailey dump valve, i know not to every ones taste, but when i back off the throttle, i get the sound from the dump valve, but then i get a bang/pop from the exhaust, just want to check this is normal or if something is wrong??
any help would be great, cheers guy's.

 

Its normal.Its excess fuel in the exhaust lighting up.Do you have a de-cat.My only concern would be if you have a cat it may be lighting up in the cat which aint gonna do it much good.The over fueling is caused by the valve venting measured air to atmos rather than back into the intake system.

 

perfectly normal mine does that all the time accompanied by some big flames

 

cheers guy's, not sure about the cat? i do have a full hayward & scott system though, how much should i be looking at for a 90,000 mile service?
sorry its my first scooby

 

Probably a de-cat then,Look out for flames in the dark