I was wondering if anybody has attempted to modify the lower stock air intake box on a R53 mini cooper s. By opening the bottom where the stock 1"? hole is and expanding it completely in the area I have marked in red. While keeping the original paper panel air filter in place.

Would this even provide the gain needed with a 15% pulley reduction or should I just stick to getting an alta/m7/ etc CAI on to my 03 MCS?

If this has not been attempted I was thinking about trying it before moving onto the larger aftermarket CAI's. Anybody else's thoughts?

 

the paper filter wont do you any good. and, a box is a box really.

IMO, best value would be to cut a big hole in the airbox, on the top portion at the back, to simulate a JCW airbox. Then, get some sort of high flow filter. Amsoil makes a good one (mine) and of course theres your K&N style (oiled) filters.

next, spend the rest of your $$ on a silicone intake tube.

thats my 2 cents!

 

If you just cut the box, you make a HAI (hot air intake), since you will just get hot air from the engine bay....a few folks hace done this, but if you cut the wrong side of the box....lol.
The stock filter box does (should) have a tube to get cool air from the front of the car, and a opened on the back to get air from the windshield vent area....the filter is most likly the limiting factor, get a good reusable panel filter.....or just make a cai with a cone filter....mank homebrew ones around.

 

P.S
the silicone intake tube looks nice, but no diff on a dyno.....heck if you FEEL the inside of a silcone tune it is rougher than the stock....i would put the intake tube right up there with a COIL PACK" upgrade...looks, but minimal gain per $$ spent, if any.

Many folks have enlarged the openings, but a cai cone filter did more...especially for sound. Only 1 or 2 hp is added by a cai...so it is MOSTLY for sound/looks.

 

This thread is worth a read:
https://www.northamericanmotoring.co...ir-intake.html

- Andrew