davelv72 said:
Do fresh air intakes really do much? Also what type of rims do you like and if I increase to 17" will it still fit where my spare is now?
Yes,
cold air intakes do add some hp/tq. You bought the wrong car if you're looking to put down some serious numbers though, believe me. BMW engines are already engineered to squeeze out close to optimal performance, the bolt-ons available to us squeeze the smallest amounts of extra power out..
The addition of a intake, software, and exhaust, will net you 20-25hp/tq gains, at best on a 323/325. Headers, around 15hp or so, underdrive pulley, maybe another 5.
That said, the gains are noticable, and the software itself makes a few favorable changes (removes limiter, raises redline to 7000RPM, reduces delay in response from the accell pedal (This may be a drive by wire deal only - but my accell pedal reaction is MUCH better now)
Best bang for the buck, is to just go ahead and get a supercharger, they run 5-7k, with around 1-2k install cost.
As long as your wheel's diameter does not change, a 19" should fit in there with low profile tires. When you get big wheels, you reduce the tire size, so that you match your original wheel specs.
EX: My car came with 15's, and 195/65/15's on it (thin yet tall 'luxo ride' tires). I now run 18's, with 225/40/18, the diameter of this wheel is exact to the original 15's. No change to my speedo needed.
Absolute #1 mod I'd make first - Suspension. You can add power later, upgrade the suspension so you can handle what it already has (slow or not, even a 325 w/ a good suspension will scream on the roads..)
Welcome aboard!