car have a loud backfire when i hit around 7800 RPM in my turbo s2000 with WOT. I see some white smoke came out when i look in the rear view mirror. it sound like a gun shot. car wasn't doing this couple days ago when i got it tuned. check spark plug and regab to .026" and it's still doing it. Spark plugs going out?

 

to much horsepower!!

 

i havn't even release the gas pedal yet.. and it already backfiring

 

NVM it fix! it was bad spark plug