hi everyone. i just got a 2002 WRX that came with an after market down pipe (not sure what brand) spearco intercooler and borla exhaust. i just got an HKS SQV BOV. after i got the BOV my car started to back fire. i was wondering why its doing that. another thing is when i put the car in reverse it makes a loud winding noise. it doesnt sound normal. i was wondering if thats normal on WRX's.