Will the car not need a better flowing exhaust. If more air goes in, more has to be able to come out. I thought.... confused

2001 Cavalier
150-175 more kms
per tank of same size
Pioneer 12 CD Changer

SOLD Green 98 Mystique
GS Sport
Zetec ,ATX
885 Fogs mod.
Hi beam mod.
205 15s