single exhaust B7 A4 2.0T
 

guys.. can anyone can help me correct the usage of a single pipe exhuast.. using stock downpipe i connected my mandrel bent pipe with a cheap ass exhaust.. but for some reason.. its just fucking loud but did not notice any HP increase.. or its just me.. is there any correct way of putting it or someone making one? help please..a nd do i need a defouler to do it.. check engine light seems to be ok though... thanks pepz! looking forward to your replies..:D