most people with 316is know its not going to be a performance car
modification goes for mostly a slight improvement and just like any other car, for individuality
in my case, i went for an air filter and exhaust - not expecting any significant gains but only to improve the cars performance even slightly
in my opinion, i would not put m3 bumpers and the likes - its not an ///M3 to begin with - that just for me
but modification for the 316i is basically the same for any other e36 sedan!
* hartge, ac schnitzer, alpina, breyton and the likes have bolt on kits for non ///M3 sedans
as for breyton, they have there own front bumper - i have one laying in my garage but i choose to use my AC Schnitzer chin instead - which is bolt on to my oem bumper
here's a pic
bumpers have the size and dimensions so to speak for the sedans (non ///M3) - they only vary in the design of the lower grill - as far as i know, the 92 - 95 models have the lower grill integrated to the bumper while the later e36 sedans have the lower grill separated and therefore can be taken out
here's my ACS front lip - check the ACS site for details on pricing and stuff
* wheels - so much to choose from oem BMW wheels to aftermarket ones. id choose wheels dependent on the look you want - straight ACS, Breyton, Hartge, Alpina and so on
i personally wouldn't mix and match makes or manufactureres products (that's just me) hehehe!
PERFORMANCE - even for slight performance
* air filter - k&n, pipercross, dinan etc.
* headers, exhaust - supersprint, remus, borla etc.
k&n air filter
custom exhaust - check the link below for a video of it
* bilstein, h&r, eibach, tein
* strut bars (front and rear)
drop the car!!! hehehe - cornering was never that fun and that great
* limitless options
but in my opinion, i'd stick to blaupunkt for that german feel as your car is. blaupunkt has exceptionally good head units, speakers, subwoofers and amplifiers enough to satisfy the audiophile in anyone
* limitless as well
i went for gray face gauges and chrome trims
hope this helps out!