i went to muffler shop yesterday to find out how much a custom intake would cost... its about $30 very affordable. Stock intake is about 2.5" (not sure) but which one do you think would be better? 3inches or 3.5 or 4? i thought bigger would be better since more mass but my friend says smaller is better cause it gives more velocity...i need your help! thanks

 

if your runnin naturally aspirated, without major modifications (headwork, High comp) 2.5-3 will be more than enough, 4 is pretty extreme for a 1.6 liter engine.

 

Its just like your exhaust. If you go too big you loose velocity, and you loose the scavenging that takes place. Go too small You get excellent scavenging, but you choke the motor too much to make it worth anything.

The size would all depend on engine displacement and what types of revs your motor will be running. I would look into what size the popular companies are building theirs, and copy them.

EDIT:: 700th post and only after like 3 years of being a member of HT