back fire?

[George89]

hi i know this might be normal and i am just sounding stupid but i just want to know. When i drive at high revs and jump of the gas i hear back fire from my exhaust is that normal? also i got nos octaine booster which i haven't tried yet but i heard aparently it killed some peoples engines using it? could that happen?

thank you for your replies

 

[_JT]

Car specs? Stock exhaust?

 

[George89]

honda civic ej9 1.4 D14A4
Everything is stock except exhaust and filter. I aint to sure on what exhaust it is as i bought it like that. but i really don't like the look of the exhaust. also it is just a back box not cat back.

 

[Darragh]

Theres no point in using octane booster in a non-jap import !!