BMW 323 Forum : “How can I essentially make my 323i as fast as an m3?”

having the k&n and full exhaust wont harm it as i have it done to my bmw 323i and mine has 159,000 miles on the clock u could get a throttle intake of a 325i and fit it to give u more power u will need the kit witch u can find on ebay but also if ure getting a k&n get a direct replacement filter for ure original air box as its better for the car or the other option is turbo as they now do a turbo kit for the 323i aswell witch takes the bhp from standard to 260bhp with a ecu remap and chip u can easilly get 300+bhpregards dave good luck

You have to fix a super charge to your car engine+change the wheel rims & tires to M3 size..

No matter how you do it, it isn't cost effective. Just buy an M3.

a list of upgrades you could do that will give you some better performance are CAI, throttle body, chip, full exhaust with heat wrap, and high quality ignition system.  that would be about all i could think of for cheaper n/a mods.  some other mods you should look into is 4 wheel disc brakes (if your car doesnt already have it) with cross drilled slotted vented rotors and high quality pads.  also, you should consider upgraded shocks and struts.  better handling and grip from your car would make a world of difference.   but in order to get your car as fast as an m3 youre going to need to put some serious cash into it.  i would suggest the mods i listed with that car or sell it and get a 335 then add the performance package.  

i have modded mine with induction kit full stainless 2 3/4ins exaust with twin tail pipes, decat & its done 235000miles it still goes like stink & drives beautifully, next is to use m50 inlet manifold(328)