It's usually best to match the pipe size to the size of your throttle body. There's no sense in having a pipe that's so big or so small that it doesn't match up, plus the rubber thing that attaches them together would be difficult to do...

Tell Apexi or whomever that the filter needs to fit on the end of a 2.75" pipe, they should understand.

Do you really think his MPG went down because there was 20% more air in that intake? He most likely started driving it more aggressively to here the sound.

 

could be...but i drive somewhat aggressively and even my gas mileage didn't look as horrible as his...he had a full tank by friday and was half way through it by sunday morning and the only places he went was school and his girl house which aren't to far from his house

 

Most intakes are 3". There won't be too many filter options for 2.75 I don't think. The pressure drop that is going to control the engine is at the throttle body so the MPG drop is from your friend flooring it too much. SRI gets 1 or 2 more ft.lbs. of torque. CAI gets 1-2 more HP. SRI is louder in the cabin due to opening location. Hydrolock is not much of a concern unless you have major amounts of snow or like to drive through lakes and rivers, but then you have bigger issues. AF mixture is controlled by the O2 sensors in the exhaust, not the intake.

& the search button could have told you all of these things. I learn through research.

 

right now his pipe i did for him is about 2.5" or 2.75" but i know for sure it isn't 3"...
and your right,but damn is it really possible for a corolla to burn my gas then an accord?because i tend to cruise but sometimes will unleash the beast, but he's more on the cruising side