BMW 323 Forum : “Can the BHP be increased to that of a 325i? If so how do you go about it?”

There are aftermarket computer chips available that claim to boost horsepower.  I would look into the availability of one of them.  Search for BMW Performance chips.

there's a couple of flash tuners, one called a shark injector found on namotorwerks.com. and the other is bavarian
auto's version at bavauto.com.  is yours a 98,99, or 00?  partial the reason for the different numbers is the double
vanos system on the later models of 325's.

start with the cheap basics... high flow air filters and synthetic oil. If you like the sound (I don't), but get an exhaust, it will increase hp and decrease back pressure.  after that... then you could go to the chips... unless you like playing with the engine itself, but they don't make a lot of aftermarket parts for those cars

Tuning is easy I'd scew the distributor and just do it yourself. Remember though upgrading your car could affect any type of warranty on your vehicle. Even simple putting an upgraded filter can do it. But anyway if you want a lot of power for a good amount. Look into AFE dry cold air intakes, Free flow exhaust. The performance chips really don't give you as much high power performance as some people might belive. Besides the cost to get a good chip and have it installed is pretty hefty. I personally go with Dinan but you might pay 400 bucks for the program itself plus how much the dealership wants to install it. I'm not agianst chips at all but I'd suggest waiting for a bit. I don't know if your car is manual or not. If you have an automatic thats probably the biggest thing holding you back from your speed you want. But they do make chips for the transmission to adjust their shift time and power out puts that might be the route to go. Anyway if you have more questions you can find me at bavarianpower.com.

It is not the same engine, therefore you just cant tune it to get greater power.

True, the cylinders and engine size are....